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The overwhelming majority of Americans believe in God; this conviction has existed since the beginning of recorded time and is shared by billions around the world. In The God Gene, Dr. Dean Hamer reveals that this inclination towards religious faith is in good measure due to our genes and may even offer an evolutionary advantage by helping us get through difficulties, reducing stress, preventing disease, and extending life. Popular science at its best, The God Gene is an in-depth, fully accessible inquiry into cutting-edge research that can change the way we see ourselves and the world around us. Written with balance, integrity, and admirable scientific objectivity, this is a book for readers of science and religion alike.
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Cover Page
Title Page
One Spiritual Instinct
Two Self-Transcendence
Three An Inherited Predisposition
Four The God Gene
Five Monoamines and Mysticism
Six The Way Things Seem
Seven How the Brain Sees God
Eight Evolving Faith
Nine Religion: From Genes to Memes
Ten The DNA of the Jews
Eleven God Is Alive
Sources and Further Reading
Copyright Page

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To Donald and David,
my spiritual guides

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Religion and spirituality are topics far removed from my professional expertise in molecular
genetics. Without the help and encouragement of friends and colleagues from many disciplines, I
could never have written this book.
I owe special thanks to Ronald Green, professor of religion and chair of the Ethics Institute at
Dartmouth University, who early on helped me focus on the personal aspects of religion. Ron
steered me to the right questions, even though he still fundamentally disagrees with my answers.
Gerald Edelman, the Nobel laureate biologist who now directs the San Diego Neuroscience
Institute, is another skeptic who nevertheless provided me with deep insights into the brain and
Robert Cloninger, a physician-scientist who is professor of psychiatry, genetics, and
psychology at Washington University School of Medicine in St. Louis, played an important role
in convincing me that spirituality is a measurable quantity. His self-transcendence scale is central
to the book, and I have always profited by our interactions.
Lindon Eaves, who is both a professor of human genetics and psychiatry at Virginia
Commonwealth University and an Anglican priest, provided much insight and knowledge about
how spiritual and religious values are transmitted. I thank Susan Blackmore, a senior lecturer in
psychology at the University of th; e West of England, Bristol, for being so unselfish in
communicating her insights into memes. Lee Dugatkin, associate professor in the Department of
Biology at University of Louisville, Kentucky, and author of several books about animal
behavior, greatly impacted my thinking about evolution and group selection.
Both Andrew Newberg, director of nuclear medicine at the Hospital of the University of
Pennsylvania, and V. S. Ramachandran, who is director of the Center for Brain and Cognition at
the University of California, San Diego, and adjunct professor of biology at the Salk Institute,
provided insight into the ingenious neurobiological methods they have developed to probe the
role of the brain in spirituality and belief. On the molecular side, George Uhl at the National
Institute on Drug Abuse was kind enough to share with me his vast knowledge of monoamine
transporters and their genes, including VMAT2.
The chapter on the DNA of the Jews could not have been written without the help of David
Goldman and Neil Bradman in London, England, and Karl Skorocki in Haifa, Israel, who were
kind enough to spend time with me explaining both the science and the fascinating personal
stories behind their research. Also in Israel, Bob Belmaker, Jon Benjamin, and Dick Ebstein
provided both sage advice on psychiatric genetics and a guided tour of the multicultural
synagogues of Beersheba.
I learned much about witchcraft and the religious construction of gender from my cousin
Wendy Griffin, professor of women’s studies at California State University, Long Beach.
Through Wendy, I met the formidable high priestess and teacher of the Wiccan way, Vivianne
Crowley, who lectures and writes about paganism in England.
I had the great fortune to meet James Austen, author of Zen and the Brain, at a conference in
Kyoto, where he provided sage advice on both the neurobiology and the practice of Zen
Buddhism. It was during the same trip that I visited the Hosenji Zen Center, where Tenkai and
several monks were kind enough to discuss their own unique insights into Zen.
Julie Castiglia, my agent, and Roger Scholl, my editor, were instrumental in convincing me that
people might actually read a book that mixed the seemingly incompatible topics of religion and
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science. I thank them for their guidance, patience, and formidable editing skills.
I owe thanks to several organizations and institutions as well as individuals. The Templeton
Foundation is a terrific source for information about religion and science through their Web site,
newsletters, and sponsored lecture series. The Zygon Center for Religion and Science publishes
Zygon, the premier academic journal on religion and science, while Science and Spirit Resources
publishes the accessible periodical Science and Spirit.
For the past twenty-eight years, the National Institutes of Health has provided me with a superb
research environment and many talented colleagues. I would like to emphasize, however, that
this book was written strictly as an outside activity with no financial support or institutional
encouragement from the United States government. The ideas expressed here are solely my own.
My greatest inspiration was William James, whose Varieties of Religious Experience has
provoked my thinking about the role of biology in culture ever since I first read it for a
psychology course as an undergraduate. His belief that there is a fundamental divide between
private and public religion is central to my thinking. Although James lived long before genes and
DNA were discovered, I like to think that he would fundamentally agree with the thesis of The
God Gene.
Lastly, I thank my partner, Joe Wilson, and my spiritual guides, Donald and David, for
standing by me through thick and thin.

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Spiritual Instinct

Instinct leads, logic does but follow.
—William James

The first thing I noticed about Tenkai was his smile. It was serene, content, knowing but not
smug. It was the smile of a person at peace with himself and the world around him. The smile of
someone who had seen much but could still be surprised. It was a spiritual smile.
The second thing I noticed was that even though Tenkai spoke fluent Japanese, wore traditional
Japanese garb, and was living in a Japanese monastery, he was clearly not Asian. His blue eyes
and light brown hair were the giveaway. He, in fact, was born and raised in Hamburg, Germany,
as Michael Hoffman.
I met Tenkai at the Hosenji Zen Center, which is located in a small Japanese village about an
hour’s train ride west of Kyoto. The Center provides a venue for people from different countries
and religious traditions to learn about Zen Buddhism and practice its system of meditation,
known as zazen, in which one sits in the lotus position with half-closed eyes and focuses on
breathing. The idea is to empty the mind of all thoughts.
I participated in the Center’s daily activities: waking to a gong at 6 A.M., an hour of zazen
sitting in a traditional tatami mat room overlooking a waterfall, eating a breakfast of rice gruel
and pickled vegetables in silence, several hours of weeding the vegetable garden or sweeping the
stone paths, sutra chanting, supper of more rice and vegetables, and a final two hours of
meditation in a log cabin overlooking a temple. It was a peaceful life. But I was not at the Center
to ripen my intuitive faculties or to experiment with monastic existence. I was there attempting to
understand whether or not there is a biological basis of spirituality.
Until the age of twenty-four, Tenkai led an ordinary life as a high school teacher. Following a
breakup with his girlfriend, however, he began to ask himself the life questions at the heart of
our need to believe in something larger than ourselves. Why was he here? What is the purpose of
life? Why is there so much suffering? Soon thereafter he quit his job, got on his bicycle, and
started pedaling east. He didn’t stop until he reached the shores of the East China Sea.
Along the way, Tenkai experimented with every spiritual system and mystical tradition he
encountered. In Austria, he studied the principles of anthroposophy, which claims to be “a path
of knowledge which leads the spiritual in the human being to the spiritual in the universe.” In an
Indian ashram, he practiced a type of meditation in which bouts of exuberant dancing and
singing were alternated with periods of complete motionlessness. He prayed for twelve hours a
day at a monastery in Nepal, and in China he practiced the graceful motions of Tai Chi.
At times he fasted and abstained from sex, while at other times he mixed alcohol, drugs, and
women with abandon. There were times when he sat quietly for hours; at other times he jumped
about and grunted like a gorilla. But no matter what he tried, no matter which spiritual leader he
followed, Tenkai felt that something was missing. It wasn’t until he abandoned his bicycle and
flew to Japan that he found what he was looking for: Zen Buddhism.
Zen is based on the premise that every human being is capable of enlightenment. All that is
needed is to see through to one’s true nature through meditation. The emphasis is on living in the
present with no regret for the past or fear of the future. The motto on the Hosenji Zen Center’s
brochure, for example, is “Your future is here now.”
Zen is unique among religions in that it is virtually devoid of theology, scripture, or ritual.
There are no gods or devils, there is no heaven or hell. Although Zen does have priests, they do
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not have any special claim to holiness.
When I met Tenkai, he had just completed his apprenticeship at the traditional monastery of
Empuku-ji and started residency at the Hosenji Center. The monastic life seemed to suit him
well. Slowly, he told me, things began to change for him. It wasn’t so much that the monastic life
changed the way he felt—he still had emotional ups and downs—or the way he thought. Zen
isn’t about cognition, he explained. Instead it changed the way he perceived things. He felt he
was more integrated with the universe, his sense of reality more focused. What changed, he says,
was his sense of the way things are—his consciousness.
Sometimes this new sensibility came upon him when he was practicing zazen. Other times it
occurred when he was performing hard physical labor. Asked what it felt like, he told me, “I
can’t explain it in words, but once you have the feeling you’ll understand. It’s like your mind just
isn’t there.”
When I admitted to Tenkai that I spent much of my meditation time fretting about routine
matters, he gave me a spiritual smile. “It’s a strange and mystical thing, this feeling. But don’t
worry,” he said. “Everybody gets it at one time or another.”
A Human Universal

Although Tenkai may be unusual compared to the average person in the strength and tenacity of
his metaphysical yearnings, he is by no means unique. Most people, psychologists and
theologians would argue, have some capacity for spirituality. It is among the most ubiquitous and
powerful forces in human life. It has been evident throughout recorded history in every
civilization and culture, in every nook and cranny of the globe. For many people, it is the main
focus of their lives.
Homo sapiens have had spiritual beliefs since the dawn of our species. More than 30,000 years
ago, our ancestors in what today is Europe painted the walls of their caves with images of strange
chimeras with human bodies and animal heads, representing, anthropologists feel, sorcerers or
priests. These early humans buried their dead with elaborate preparations for the afterlife.
Sometimes they equipped them with food and supplies for their journey; other times they cut off
their hands and heads, perhaps to prevent the return of enemies. These are the actions of
Our spiritual convictions remain just as strong today. Surveys show that more than 95 percent
of Americans believe in God, while 90 percent meditate or pray, 82 percent say that God
performs miracles, and more than 70 percent believe in life after death.
Our faith is not unique. Even in China and the former Soviet Union—where powerful
governments used every possible form of persuasion to replace God with Communism—more
than half of the people retained their spiritual beliefs. Meanwhile, the forces of fundamentalism
—whether Christian, Jewish, or Muslim—are sweeping across the globe from South America to
the Middle East to Africa.
Our spiritual beliefs are not necessarily reflected in terms of church attendance, however. In
fact, church attendance has been declining in the United States ever since the 1950s. More and
more people feel that churches place too much emphasis on organization and not enough on
spirituality. As noted in one Gallup poll, “believing is becoming increasingly divorced from
Church attendance in Europe has declined even more dramatically. In England and Holland,
only 5 percent of the population attends religious services on a regular basis. Even in Italy, often
considered a bastion of traditional Catholic values, the majority of people disagree with the Pope
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on religious issues such as divorce and abortion.
The discrepancy between flagging attendance in formal religious settings and the high
percentage of people who believe in God can be explained in large measure by the fact that
spirituality is distinct from the precepts of any particular religion. More than three-quarters of
people surveyed feel that God can reveal himself through many different paths. There is a
growing sentiment that it doesn’t matter what church you go to because “one is as good as the
Despite formal religious adherence or attendance, a survey taken in the 1990s found that 53
percent of Americans have had a “moment of sudden religious awakening or insight.” In our own
research at the National Institutes of Health, more than one-third of the essentially random
collection of people we surveyed reported personal experiences in which they felt in contact with
“a divine and wonderful spiritual power.” A similar percentage of people said that they have, at
least once or twice, felt “very close to a powerful, spiritual force that seemed to lift you out of
yourself.” Although such experiences were once regarded as signs of incipient psychopathology,
recent research shows that they actually are associated with better adjustment and psychological
health in most people.
While someone like Tenkai may be at the high end of the human continuum in terms of his
interest in spirituality, he is by no means unique. He stands out in the degree of his spirituality
rather than in the fact that he believes in something larger than himself. He just has more than the
usual degree of what in fact is a common human trait.
The God Gene Theory

Why is spirituality such a powerful and universal force? Why do so many people believe in
things they cannot see, smell, taste, hear, or touch? Why do people from all walks of life, around
the globe, regardless of their religious backgrounds or the particular god they worship, value
spirituality as much as, or more than, pleasure, power, or wealth?
I argue that the answer is, at least in part, hardwired into our genes. Spirituality is one of our
basic human inheritances. It is, in fact, an instinct.
At first, “instinct” may seem to be a peculiar word to pair with spirituality. We usually think of
instincts as automatic, unconscious reactions or behaviors that are performed without thought or
training. Birds know to fly south for the winter by instinct. Blinking your eyes when someone
takes a swing at you is an instinct. A newborn baby learns to suckle at her mother’s breast by
instinct, not because she has been taught. It is instinctual to become aroused when presented with
a sexual stimulus. By contrast, spiritual behaviors such as meditating in the lotus position or
taking communion are neither automatic nor unconscious. They are highly deliberate and
culturally learned activities.
I do not contend that spirituality is a simple instinct like blinking or nursing. But I do argue that
it is a complex amalgamation in which certain genetically hardwired, biological patterns of
response and states of consciousness are interwoven with social, cultural, and historical threads.
It is this interdigitation of biology and experience that makes spirituality such a durable part of
the fabric of life—a rich tapestry in which nature is the warp and nurture is the woof.
The idea of complex characteristics that are influenced by both genes and environment is not
unique to spirituality. There are many well-known examples of the interplay between nature and
nurture, even among animals. Consider the song of the white-crowned sparrow. The male
sparrow’s song, which he begins to sing at about seven or eight months of age, consists of a long,
low whistle followed by a series of trills. That the song is at least partly innate can be seen by its
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species specificity: All male white-crowned sparrows sing basically the same song, even when
they are separated from their parents after two weeks and raised in complete isolation from any
other birds. Moreover, there is a dedicated brain circuit for song, consisting of six interconnected
brain regions that control the vibrations of the vocal membranes in the throat. (Three of the
regions are sensitive to sex hormones, which explains why only males produce the characteristic
mating song.) The reason a sparrow sings the song of a sparrow, and not of a robin or a lark, is
that it has the genes and brain of a sparrow, not that it was raised by sparrows.
But experiments show that the song is also partly learned. Sparrows from different areas sing
slightly different varieties of the song, or “dialects,” that differ in the exact number and
placement of the trill notes. When sparrows are left with their parents for the first three months
of life, then raised in isolation or with foster parents from another region, they still sing the
parental dialect when they begin to vocalize a few months later. By contrast, when the young
birds are taken from the nest after only a few weeks, then raised hearing tape recordings of a
different dialect, they sing the foreign song.
An even more profound effect of the environment has been shown in studies in which the
chicks have been deafened at an early age. These poor animals never produce anything more
than a few unconnected notes, no matter how hard they try. They need to hear themselves to sing
Such experiments show that while the basic species-specific skeleton of the song is hardwired
in the genes, it requires the environmental clue of being able to hear its own voice to be
triggered. And while the precise details of the song are culturally transmitted during a critical
period early in life, they require the right biological machinery and genetic code to be actualized.
It’s part of the remarkable yin and yang of nature and nurture, especially in a species that most
people would never even associate with having a culture.
In The God Gene, I propose that spirituality has a biological mechanism akin to birdsong, albeit
a far more complex and nuanced one: that we have a genetic predisposition for spiritual belief
that is expressed in response to, and shaped by, personal experience and the cultural
environment. These genes, I argue, act by influencing the brain’s capability for various types and
forms of consciousness, which become the basis for spiritual experiences.
The term “God gene” is, in fact, a gross oversimplification of the theory. There are probably
many different genes involved, rather than just one. And environmental influences are just as
important as genetics. Finally, spirituality, in its broader meaning, is about much more than
belief in a particular God. Some of the most spiritual people I’ve interviewed and discuss, such
as Tenkai, don’t believe in a deity at all. Nevertheless, I felt it was a useful abbreviation of the
overall concept.
The Fivefold Way

Proving there is a genetic component to spirituality is no simple task, and probably no single line
of evidence or observation will be completely convincing. It’s not like hair or eye color, which
are passed from one generation to the next in an obvious way. Therefore, I use several different
lines of reasoning and types of data in the book to show the instinctual side of spirituality. Some
of them are based in traditional approaches to religion such as psychology and anthropology. The
main emphasis, however, is on powerful new research methods that have been developed in
molecular genetics and neurobiology. The proof, in other words, depends on the whole pudding
—the entire array of evidence—not just one ingredient. Let me summarize the five essential
arguments I intend to present:
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Measurement. The first task for any scientist attempting to link genetics to spirituality is to
show that spirituality can be defined and quantitated. This is essential for any scientific analysis,
regardless of the topic. Scientists measure things. If we can’t measure it, we can’t test a
hypothesis about it, and if we can’t test a hypothesis, it can’t be proved.
Measuring spirituality is particularly difficult because it encompasses so many different types
of feelings, beliefs, and experiences. Fortunately, a number of psychologists have tackled the
problem using sophisticated statistical methods of psychological measurement. In the book, I use
a scale called “self-transcendence” developed by Robert Cloninger, an innovative thinker who
studies the biological and social origins of personality.
Self-transcendence provides a numerical measure of people’s capacity to reach out beyond
themselves—to see everything in the world as part of one great totality. If I were to describe it in
a single word, it might be “at-one-ness.”
Although self-transcendence might seem a bit “flaky” to some readers, it successfully passes
the tests for a solid psychological trait. It basically is a yardstick for what is often referred to in
the West as faith, or in the East as the search for enlightenment.
One of my biggest challenges in The God Gene is to attempt to separate spirituality from
religion. This is difficult because religion is founded on spiritual beliefs. Conversely, spiritual
beliefs usually are expressed using the language and rituals of religion. Nevertheless, the selftranscendence scale tries to separate one’s spirituality from one’s particular religious beliefs by
eschewing questions about belief in a particular God, frequency of prayer, or other orthodox
religious doctrines or practices. Even individuals who dislike all forms of organized religion may
have a strong spiritual capacity and score high on the self-transcendence scale.
Heritability. The next task for the scientist exploring the link between genetics and spirituality is
to determine whether spirituality is inherited, and if so, to what extent. This can be tackled by
using twin studies—comparing identical twins, who have the exact same genes, to fraternal
twins, who are only as genetically similar as ordinary siblings. One can determine a factor’s
heritability by comparing resemblances and differences between different types of twins, and
between twins and unrelated people.
Scientists have used twin studies to show that spirituality, as measured by the selftranscendence scale, is significantly heritable. The extent of genetic influence is similar to that
for many personality traits, and even greater than it is for some physical characteristics. In other
words, there is a strong genetic link.
Twin studies also can be used to study the role of the environment on a trait or behavior. Not
surprisingly, upbringing plays an important role in spirituality. But remarkably, what counts
most is not the specific shared cultural environment, such as Sunday school, sermons, or
parenting. What is important are the unique life events each person experiences on their own.
Identifying a Specific Gene. While twin studies suggest that spirituality is partially inherited,
they say nothing about which genes are involved or how they work. That’s the job of molecular
biology. One major new finding revealed in The God Gene is our discovery of a specific
individual gene associated with the self-transcendence scale of spirituality. This “God gene”
codes for a monoamine transporter—a protein that controls the amount of crucial brain signaling
chemicals. Interestingly, these same brain chemicals can be triggered by certain drugs that can
bring about mystical-like experiences.
The specific gene I have identified is by no means the entire story behind spirituality. It plays
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only a small, if key, role; many other genes and environmental factors also are involved.
Nevertheless, the gene is important because it points out the mechanism by which spirituality is
manifested in the brain.
Brain Mechanism. The monoamines I identify—the brain chemicals controlled by the God gene
—have many different functions in the brain. They appear to influence spirituality by altering
consciousness, which can be broadly defined as our sense of reality—our awareness of ourselves
and the universe around us, including our thoughts, memories, and perceptions.
The intimate relationship between spirituality and consciousness becomes most conspicuous
through mystical experiences, such as Saul’s conversion on the road to Damascus, which are
invariably accompanied by major alterations in perceptions. But the relationship between
spirituality and consciousness also is evident in more subtle forms, such as self-transcendence, in
which consciousness is altered by a blurring of the normal distinction between self and other.
Monoamines such as serotonin and dopamine are important players in consciousness.
According to a theory developed by Gerald Edelman, the key role of monoamines with regard to
consciousness is to link objects and experiences with emotions and values. Evidence supporting
the importance of monoamines in affecting consciousness may be seen with the help of
sophisticated brain-scanning techniques and by analyzing the actions of various types of drugs
that block or enhance these brain chemicals, as well as in studies of individuals with brain
lesions such as temporal lobe epilepsy.
Selective Advantage. Darwin’s theory of evolution and competitive advantage applies as much
to complex human behavioral characteristics such as spirituality as it does to beak shape in birds
or hunting ability in lions. What are the selective advantages of having God genes? Are they
simply a side effect of the evolution of the mind, or do they offer us a more direct evolutionary
I argue that one of the important roles that God genes play in natural selection is to provide
human beings with an innate sense of optimism. At the psychological level, optimism is the will
to keep on living and procreating, despite the fact that death is ultimately inevitable. At the
physical level, studies show that optimism seems to promote better health and quicker recovery
from disease, advantages that would help us live long enough to have and raise children and pass
on our genetic heritage.
These five lines of reasoning and evidence are the heart of the book. In the last part of The God
Gene, I turn to the broader questions posed by the interface of spirituality and biology with
religion and society.
From Spirituality Genes to Religious Memes

Spirituality is an intensely personal activity. It involves private feelings, thoughts, and
revelations. These are often difficult if not impossible to describe, much less to share. Yet only
rarely does spirituality occur in a complete vacuum; even the most isolated ascetic must
sometimes come in contact with other people. More often than not, spirituality is associated with
a much more public domain of human life: religion.
Of course, religion in human society is far more than just a public manifestation of spirituality.
Religious institutions act as schools, courts, sanctuaries, landholders, and counselors, as well as
places of worship and prayer. What do these diverse functions have to do with the biology of
To find out, scientists used the same experimental approaches described earlier to show that
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spirituality is heritable and applied them to traditional religious behaviors and attitudes. The
results showed that although religiousness does have a genetic component, it is much weaker
than that for spirituality. Religion, unlike spirituality, is transmitted primarily not by genes, but
by memes: self-replicating units of culture, ideas that are passed on from one individual to
another through writing, speech, ritual, and imitation.
While it is our genes that initially make us receptive to spirituality and faith, it is our memes
that carry religion from one generation to the next and that make each religion distinct. Later, I
discuss how such memes work, and the ways in which spirituality glues them together into
coherent and enduring religious institutions.
One of the strongest of all religious memes is the concept that it is a sin to marry a nonbeliever.
In Chapter Ten, I show the extent to which one group, the Jews, have embraced and followed
this proscription. DNA fingerprinting demonstrates that Jews all around the world—from the
Middle East to the Midwest, from the Jewish ghettos of Europe to the villages of sub-Saharan
Africa—have preserved the same telltale pattern of DNA snippets. Despite the diaspora, the
Inquisition, and the Holocaust, Jews have sustained their genetic heritage as well as their
religious traditions. Remarkably, the coalescence of these telltale DNA sequences can be dated to
approximately 3,000 years ago—the time of the exodus from Egypt, according to the Bible.
In the final chapter, I consider the findings of The God Gene in the context of human history.
Spiritual beliefs have been with us since recorded history and, despite the growth of scientific
inquiry in the past century, show no signs of weakening. God is not dead, to answer Time
magazine. There is, however, a growing tendency to pit science and spirituality (or religion)
against each other as if they were intrinsic enemies. They are not. As Albert Einstein famously
commented, “Religion without science is blind; science without religion is lame.”
While the question “Is there a God?” may be beyond science, the question “Why do we believe
in God?”—in other words, an understanding of the mechanism through which our belief in God
or a higher power works—is potentially within our understanding.

Every good scientific treatise or book has a section on “limitations”—a listing of potential
weaknesses, flaws, and ambiguities in the data and its interpretation. This is part of what makes
the scientific method so powerful. Scientists do not jump to conclusions without looking at the
quality of the evidence. (If only candidates for political offices listed their limitations in the same
This book has three major limitations that I want to emphasize up front.
First, this is not a complete explanation of spirituality. Genes can account for part of the story
of spirituality, but not all of it—not by a long shot. For one thing, the key empirical research is
based on a single measure of spirituality, the self-transcendence scale. As I describe in the next
chapter, self-transcendence is a valid, robust, and fairly general yardstick for spirituality; high
scorers, like Tenkai, whom I introduced at the beginning of the book, would be considered
spiritual by most people. But such a scale is by no means comprehensive. Spirituality is too
multifaceted to be captured in its entirety by a single measure.
Furthermore, genes explain only about half of the variation that is seen even for this one scale.
And the single gene I’ve identified is responsible for less than that—a small percentage of
variance at best. That means that most of the observed differences are still unaccounted for. This
is the reason that spirituality can never be an all-or-nothing trait. It’s not like eye color, where the
result is either one thing or the other. It’s more graduated, like height.
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My second caveat is that behavioral genetic research can explain only individual differences,
not species-specific characteristics. What that means is that the genetic data can help explain
why Tenkai is more spiritual than somebody else, but not why humans in general are spiritual
(whereas most other life-forms presumably are not). Of course, the hope is that the same genes
that play a role in individual differences also are key players in the overall trait. That’s why I
extrapolate from our finding that a monoamine transporter gene plays an important role in
individual differences in self-transcendence to a more general theory about the neurobiology of
consciousness and spirituality. Strictly speaking, though, species-specific traits are the domain of
evolutionary psychology, a fascinating but less experimentally rigorous discipline.
My third caveat is the most important. This is a book about why humans believe, not whether
those beliefs are true. Nonbelievers will probably argue that finding a God gene proves there is
no God—that religion is nothing more than a genetic program for self-deception. Religious
believers, on the other hand, can point to the existence of God genes as one more sign of the
creator’s ingenuity—a clever way to help us humans acknowledge and embrace his presence.
Both of these arguments mix apples with oranges, or in this case, theology with neurobiology.
The one thing we know for certain about spiritual beliefs and feelings is that they are products of
the brain—the firing of electrochemical currents through networks of nerve cells. Understanding
how such thoughts and emotions are formed and propagated is something that science can tackle.
Whether the beliefs are true or false is not. Spirituality ultimately is a matter of faith, not of
I know from experience that some readers will ignore this caution, so I’ll repeat it for good
measure. This book is about whether God genes exist, not about whether there is a God.

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Feeling is the deeper source of religion.
—William James

As I began my research into spirituality, the student center at George Mason University in
Reston, Virginia, became a frequent stop. Not that it’s a particularly reverent place—on one
typical spring afternoon it was full of students chatting, studying, checking e-mail, and eating
fast food. There was a booth selling tickets to a rock concert, another with information about the
ROTC. But my interest was focused on a side lounge festooned with advertisements for research
volunteers. My own advertisement was among them; it read “Earn 40 Dollars!” (College students
will do a lot for a little cash.) The fine print explained that my colleagues and I were looking for
pairs of siblings to participate in a genetics study; participants would need to give us a blood
sample as well as answer some questions.
Inside the lounge, a dozen or so young men and women dressed in various combinations of
baseball caps, shorts, jeans, and sandals were sitting at tables. They were filling out a
questionnaire called the Temperament and Character Inventory, or TCI for short, which is a 240question true-false quiz that assesses seven dimensions of personality. My colleagues and I were
collecting the information for a study of the genetics of cigarette smoking, which was my chief
research project at the National Cancer Institute. But the TCI also happens to include a scale to
measure self-transcendence. That’s where the spirituality part came in.
Self-transcendence is a term used to describe spiritual feelings that are independent of
traditional religiousness. It is not based on belief in any particular God, frequency of prayer, or
other orthodox religious doctrines or practices. Instead, it gets to the heart of spiritual belief: the
nature of the universe and our place in it. Self-transcendent individuals tend to see everything,
including themselves, as part of one great totality. They have a strong sense of “at-one-ness”—of
the connections between people, places, and things. Non-self-transcendent people, on the other
hand, tend to have a more self-centered viewpoint. They focus on differences and discrepancies
between people, places, and things, rather than similarities and interrelationships.
Self-transcendence would become a key concept in my search for the God gene. It’s the
yardstick scientists use to gauge the intensity of individuals’ spiritual feelings. At first it might
seem simplistic to measure something as complex as human spirituality by an instrument as
quaint as a paper-and-pencil self-questionnaire. Wouldn’t it be more accurate to look at actual
behavior (what people really do) rather than self-perceptions (the way they say they feel)?
If our intent had been to measure religiousness rather than spirituality, that clearly would have
been an option. We might have explained how often people attended religious services, for
example, or whether they took their children to Sunday school. But as William James pointed out
in The Varieties of Religious Experience, feelings are what count when it comes down to the sort
of private religiousness that we now call spirituality. And since we don’t yet have any
mechanical device that can read a person’s feelings, asking questions is still the best we can do.
The critical issue is which questions to ask. That’s where psychology comes in.
The Atheist’s Discovery

One of the first modern psychologists to tackle the problem of measuring spirituality separate
from religion was an avowed atheist, Abraham Maslow.
Maslow was the founder of humanist psychology, a school of thought that became popular
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during the socially turbulent 1960s. Unlike most of his colleagues, Maslow was more interested
in the good than the bad side of our mental life. He focused on human potential instead of
psychopathology or mental disorders. To do so, he studied people he believed had actually
realized their psychological potential. He called such people self-actualizers.
Maslow’s criteria were strict. Thomas Jefferson, Eleanor Roosevelt, and Albert Schweitzer met
the grade. Benjamin Franklin and Walt Whitman did not; they were considered to be only
potential or possible cases. Out of 3,000 college students that Maslow surveyed, just one met his
definition of a true self-actualizer.
Maslow noted many similarities between the self-actualizers he identified. They were
spontaneous. They looked at even ordinary things afresh, as if for the first time, and had the
ability to see things as they really are, regardless of physical details or other people’s opinions.
They were highly ethical but not always conventional. Self-actualizers were also empathetic.
They identified and sympathized with people from all walks of life. Many of them extended their
compassion to other living things and to nature generally.
As Maslow studied more and more self-actualizers, he realized that they shared one other key
feature. They underwent periodic spiritual experiences.
This likely came as a surprise to Maslow, who took pride in being an atheist and compared
belief in God to “the childish looking for a big Daddy in the sky.” Perhaps that is why he gave
these events a new name: peak experiences. But call them what you will, the descriptions are
strikingly similar to those of spiritual revelations reported by both Western religious figures and
Eastern meditators. For example, Maslow quotes one of his subjects as saying:
I could see that I belonged in the universe and I could see where I belonged in it; I could see
how important I was and yet how unimportant and small I was, so at the same time that it
made me humble, it made me feel important.
The key feature of peak experiences is a sense of wholeness and unity with the universe, with
everything and everyone. There is an effortless letting go of the ego, a going beyond the self.
Spontaneity and creativity are enhanced, personal and physical needs are forgotten. Things are
seen as they really are, not as they serve the viewer’s needs. Maslow called this way of thinking
and feeling “being-cognition,” to distinguish it from the “deficiency-cognition” that characterizes
ordinary consciousness.
Maslow maintained that organized religion hindered rather than helped people become selfactualizers. Given his atheism, however, this may have just been prejudice. Can peak
experiences and being-cognition really be separated from more conventional religiousness?
To find out, psychologist E. L. Shostrom developed a new questionnaire—the “Personal
Orientation Inventory: An Inventory for the Measurement of Self-Actualization”—and started
giving it to subjects. As predicted by Maslow, there was an inverse relationship between scores
on this inventory and orthodox religiousness. In one study, for example, college students who
had received religious training at parochial high schools scored lower than graduates of
nonreligious schools. Other investigations showed that individuals who scored high on the selfactualization inventory were less likely to attend church, but more likely to have mystical
experiences, than were low scorers. Catholic priests scored lower than laypeople, although
transcendental meditators scored higher than nonmeditators.
These empirical studies underscored the fact that being-cognition—Maslow’s version of
spirituality, though he never would have called it that himself—is fundamentally different from
orthodox religiousness.
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Unfortunately, however, the “Personal Orientation Inventory” turned out to be a poor
psychological instrument; the subscales didn’t always hang together, the association with
mystical experiences was not reliably replicated, and scores went down instead of up with age
and experience. A better measuring stick was needed. It took another three decades to invent it.
A Spiritual Yardstick

Robert Cloninger, a psychiatrist at Washington University Medical School in St. Louis, is
perhaps the first modern-day behavioral scientist bold enough—or foolhardy enough—to have
tried to quantitate spirituality. He is the inventor of the self-transcendence scale, which grew out
of a system of personality classification called the biosocial model, and is measured as part of the
Temperament and Character Inventory.
Cloninger, a tall and thin man who walks with a slight hunch, has the distracted, absent-minded
air of a beloved professor, an image enhanced by his southern manners and soft-spoken, formal
style of conversation. His harmless appearance has fooled plenty of scientists who mistook it for
a lack of intellectual prowess.
In truth, Cloninger is a stubborn, tough advocate for his ideas and a formidable debater. Woe to
the colleague who comes unprepared; his expansive mind is filled with ready facts, references,
case histories, theories, and statistics. They are frequently needed, for Cloninger’s ideas about
the importance of spirituality are not universally accepted by his peers. In fact, most modern
psychiatrists and psychologists would just as soon not explore or discuss the matter at all. To
many of them, spirituality seems “unscientific”—a topic for priests, rabbis, and philosophers
rather than for scientists.
Cloninger was dissatisfied with standard methods of classifying personality because they were
purely descriptive. They portrayed what personality looked like but not where it came from. He
wanted a system that would reflect the underlying neurobiological and cultural sources of
individual differences.
His solution was the biosocial model, which is woven from many separate threads of
knowledge. Studies of twins, families, and adoptions were used to determine which personality
traits are more genetic and which are more environmental. The stability of personality traits over
an individual’s life span was determined from longitudinal studies that tracked individuals over
many years. Neuropharmacological and neurobehavioral studies suggested which brain
chemicals were released and which structures activated when the various traits were exhibited.
Cloninger included self-transcendence in his biosocial model because he believed spirituality
was an important part of life too long neglected by behavioral scientists. As he is fond of
pointing out, each day more people pray or meditate than have sexual intercourse. Unlike
Maslow, Cloninger is also a believer: a practicing Catholic. Ultimately, though, both of them had
the same interest. They wanted to understand spirituality separate from organized religion and
Cloninger consulted many different sources—Western and Eastern, historical and modern,
religious and secular—to develop a composite picture of what it means to be spiritual. He
scrutinized the lives of prophets and saints, mystics and seers, gurus and yogis. He read the
humanistic psychologists’ descriptions of self-actualizing people and the transpersonal
psychologists’ reports about meditators. Based on his research, Cloninger developed a scale that
is based on three distinct but related components of spirituality: self-forgetfulness, transpersonal
identification, and mysticism.

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Let me pose several questions to you. Do you ever get so involved with your work that you
forget where you are or what time it is? Do you sometimes have the feeling that you are in the
“zone” in terms of work, or sports, or music, and you can do no wrong? Have you ever been so
in love with someone that you felt like there was no boundary between the two of you?
Most people have had this type of experience at least a few times in their lives. Spiritual people
tend to have them more frequently. They score high on the TCI for self-forgetfulness, which is
the first component of self-transcendence.
It’s not easy to forget oneself. People think about themselves more than anyone else. Even
when pondering a strictly impersonal question, such as a math problem, it’s difficult not to think
about how it might affect you personally. But sometimes a task or subject is so fascinating that
you become utterly absorbed. Place and time become unimportant, personal concerns and
problems fade away. Your concentration is focused, complete.
Such absorption can happen to a painter who becomes one with the process of painting, a
musician who becomes lost in his music, a priest deep in prayer, or an ordinary person—such as
an amateur gardener who is involved in planting, mulching, and weeding and suddenly discovers
to his or her surprise that three hours have gone by. It is what psychologist Mihaly
Csikszentmihalyi calls a “flow state.” It can happen to anyone engaged in a challenging task that
demands concentration and commitment, whether they’re working, playing, enjoying a hobby, or
taking part in a relationship. What’s important, according to Csikszentmihalyi, is that the task
demands commitment and provides immediate feedback, and that the individual’s skill level is
up to the challenge.
Self-forgetfulness means having this type of “flow” on a regular basis. People often experience
flashes of insight or understanding when they are in this frame of mind. Creativity is maximized,
originality is fostered. Even the most ordinary things seem fresh and new.
The downside of self-forgetfulness is that the person may be absent-minded or “out of it.” The
opposite is true for individuals who score low for this trait. They are too self-conscious to lose
themselves in a task. They retain a strong sense of individuality even when working intensely,
playing hard, or deeply involved in a relationship. They also tend to be more conventional,
prosaic, and unimaginative than self-forgetful people.
Matteo Ricci, a sixteenth-century Italian missionary to China, epitomizes self-forgetfulness.
Ricci, a Jesuit, played a key role in introducing the Chinese to both Christianity and Western
science. Previous missionaries tried to convert the Chinese to Christianity by preaching in Latin
and teaching them European customs. They didn’t get far. Ricci thought it would be more
effective to immerse himself in Chinese culture. He ate Chinese food, lived in a Chinese house,
and dressed like a Chinese scholar. He learned to read, write, and speak the Chinese language.
Chinese is a difficult language. There is no alphabet, just 50,000 or so ideograms—a different
character for every word. Ricci had to memorize each one. He didn’t even have a dictionary;
there weren’t any. So Ricci developed a trick. He built a memory palace: a mental image of a
series of buildings in which each word was represented by a specific image in a particular
location. The word for war, for example, was symbolized by two warriors locked in combat in
the southeast corner of a reception hall. In the northeast corner was the word for profit—a farmer
holding a sickle, ready to cut his crops.
As Ricci’s vocabulary expanded, he spent more and more time in his memory palace. He
would forget about the real world for long periods of time as he wandered from word to word,
image to image. There was no room for thoughts of himself, or indeed of any real person—only
the Chinese characters and their mental pictures.
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Ricci’s self-forgetful study of Chinese paid off. Soon he could run through a list of several
hundred Chinese characters and recall them both forward and backward. Over the course of
twenty-seven years, he translated numerous biblical, scientific, and mathematical texts from
Latin into Chinese, wrote a popular Chinese catechism titled “A True Doctrine of God,” brought
the first maps of Europe into the country, and in return sent home the first accurate maps of
China. His converts were many.
Not all self-forgetful people achieve feats as prodigious as Ricci’s. Many of them are spiritual,
though, perhaps because of the way that self-forgetfulness facilitates the next two stages of selftranscendence.
Transpersonal Identification

I believe in God, only I spell it Nature.
—Frank Lloyd Wright

Are you concerned about protecting animals and plants from extinction? Do you feel a sense of
unity with all the things around you? Would you risk your life to make the world a better place?
These are some of the questions used to assess the second subscale of self-transcendence,
known as transpersonal identification. The hallmark of this trait is a feeling of connectedness to
the universe and everything in it—animate and inanimate, human and nonhuman, anything and
everything that can be seen, heard, smelled, or otherwise sensed. People who score high for
transpersonal identification can become deeply, emotionally attached to other people, animals,
trees, flowers, streams, or mountains. Sometimes they feel that everything is part of one living
Transpersonal identification can lead people to make personal sacrifices to help others—for
example, by fighting against war, poverty, or racism. It may inspire people to become
environmentalists. Although there are no formal survey data, it is likely that members of the
Sierra Club and Greenpeace score above average on this facet of self-transcendence. A drawback
of transpersonal identification is that it can lead to fuzzy-headed idealism that actually hinders
rather than helps the cause.
Individuals who score low on transpersonal identification feel less connected to the universe
and therefore feel less responsible for what happens to the world and its inhabitants. They are
more concerned about themselves than about others, more inclined to use nature than to
appreciate it.
Love of nature is a recurring theme in spirituality, from the beginnings of civilization up to the
present. “What else is nature but God?” asked Seneca the Younger, a Roman philosopher who
lived 2,000 years ago. In the twentieth century, Albert Einstein put it this way: “Try and
penetrate with our limited means the secrets of nature and you will find that, behind all the
discernible concatenations, there remains something subtle, intangible, and inexplicable.
Veneration for this force beyond anything that we can comprehend is my religion.”
Love of nature is incorporated into many formal religions, especially in the East. Hinduism
teaches love and respect for all living creatures, which is why vegetarianism is so common in
India. Members of one sect, the Jains, go so far as to cover their mouths with cloth to avoid
accidentally swallowing flying insects. The guiding principle of Taoism is to be in harmony with
the original order of the universe; turning to nature is the way to discover that order. Mahayana
Buddhism includes a vow to save all beings, while Shinto reveres the spirits manifested in foxes
and squirrels.
Although Western religions are less consistently focused on nature, they are not insensitive to
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it. St. Francis of Assisi was a famous naturalist who preached to birds and tamed a wolf. His love
for all aspects of the physical universe is seen by Christians as a kind of symbolic return to
innocence experienced by Adam in the Garden of Eden.
One example of the principles of transpersonal identification is Albert Schweitzer—medical
missionary, musician, theologian, and Nobel Peace Prize winner. Schweitzer, one of the most
acclaimed self-transcendents of the twentieth century, developed a system of ethics that he called
“reverence for life”: that everything that maintains and enhances life is good, everything that
destroys or hinders it is bad. The idea came to him while he was on one of many medical
missions deep in the jungles of Africa.
Schweitzer believed that “all life is valuable and that we are united to all this life. From this
knowledge comes our spiritual relationship with the universe.” Even the simplest life-forms were
sacred to him, and he admonished people to avoid injuring any living creature.
According to Schweitzer, all people possess an instinctive “reverence for life.” But they are
often reluctant to express it because they are afraid of being thought of as sentimental. To
Schweitzer, expressing that reverence for life was an inner necessity that arises independent of
thought or understanding. In other words, he believed that transpersonal identification is innate,
not learned. It was a prescient thought.

There is a central order to the universe, an order that can be directly apprehended by the soul in mystical union.
—Albert Einstein

Have you often found yourself moved by a fine speech or piece of poetry? Do you sometimes
feel a spiritual connection to other people that can’t be explained in words? Do you think
mystical experiences are just wishful thinking, or real?
These questions are from the third and final subscale of self-transcendence, which Cloninger
calls “spiritual acceptance versus rational materialism” but that I refer to by the simpler term
Individuals who score high for mysticism are fascinated by things that can’t be explained by
science. They see a loaf of bread that resembles Jesus or a parking space that opens up just in the
nick of time as evidence of a higher power. Often they claim to have a “sixth sense,” or
extrasensory perception. They believe in miracles.
Low scorers on this subscale are more materialistic and objective. They see an unusual loaf of
bread or an unexpected parking opportunity as nothing more than coincidence. They don’t
believe in things that can’t be explained scientifically.
Mysticism is the part of self-transcendence that most obviously relates to traditional spirituality
and religion, because it includes belief in the supernatural. Indeed, many of the world’s religions
were founded by mystical individuals such as Siddhartha Gautama, Jesus, Muhammad, Yazid
Taifur al-Bistami (Sufi Muslim), Mary Baker Eddy (Christian Science), and Joseph Smith
But you don’t have to be religious to be mystical. Scientists, too, can score high on this aspect
of self-transcendence. Albert Einstein is a prime example.
Einstein was not conventionally religious. He rejected the orthodox Judaism of his parents at
the age of twelve, disavowed the idea of a soul separate from the body, and was doubtful of an
afterlife. Nor did he believe in the conventional image of God as a personal being who is
concerned with our lives, answers our prayers, and judges us when we die.
Nevertheless, Einstein was a profoundly spiritual individual who believed that “the fairest thing
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we can experience is the mysterious.” His reverence was directed to the harmony of the cosmos,
the sheer wonder of existence. His God, who “didn’t play dice,” was “the grandeur of reason
Cloninger believes that the psychological function of mysticism is intuitiveness. In support of
this idea, he has found that people who score high on the mysticism subscale also score high for
various measures of creativity. However, individuals who score high for mysticism but lack
psychological maturity may be prone to psychosis.
Scientists often denigrate “intuitiveness” as little more than jumping to unsupported
conclusions. After all, the ostensive purpose of science is to prove things, not to make guesses.
Einstein felt otherwise. He never tried to separate his science from his spirituality. In fact, he
believed the two were interconnected. As he commented in an interview that nicely encapsulated
the connections between mysticism, creativity, and spirituality:
The most beautiful and most profound religious emotion that we can experience is the
sensation of the mystical. And this mysticality is the power of all true science. If there is any
such concept as a God, it is a subtle spirit, not an image of a man that so many have fixed in
their minds. In essence, my religion consists of a humble admiration for this illimitable
superior spirit that reveals itself in the slight details that we are able to perceive with our
frail and feeble minds.
Does It Hang Together?

Cloninger developed the self-transcendence scale based on the lives of spiritual people. Based on
his criteria, Siddhartha Gautama, Mahatma Gandhi, Albert Schweitzer, Albert Einstein, and
Tenkai would score high for self-transcendence. Genghis Khan, Queen Victoria, and Dwight
Eisenhower probably would not. It seems like a logical way to measure spirituality.
But is it really? Is self-transcendence a valid psychological trait, or is it just a mishmash of
various bits and pieces of personality?
To find out, Cloninger gave the TCI to ordinary people and then analyzed their responses to the
questions about self-transcendence to see if their answers hung together in a coherent way. The
statistical tool that he used to examine the data was factor analysis, one of the handiest
implements in the psychologist’s toolbox. It can be applied to individual items, like the questions
in a personality inventory, or to groups of items, such as the subscales for mysticism,
transpersonal identification, and self-forgetfulness. The aim is to determine whether different
items are fundamentally related to one another. If so, they may be caused by a common source.
To give an example, suppose I collected information about people’s eye color, hair color,
height, and weight. Statistical analysis would reveal two factors: coloration and size. Hair and
eye color tend to go together because they both use the same pigments; that’s why most people
with brown eyes also have brown or black hair. Height and weight go together because, given the
same fat percentage, a taller person will simply have more mass than a shorter person. Of course,
there would be some people who didn’t fit the mold—short, heavy, brown-eyed blondes, for
example—but they are the exception rather than the rule.
The same approach can be applied to personality. Cloninger’s data came from three hundred
people at a mall in St. Louis. There was nothing special about the individuals who participated.
They were just your typical mix of shoppers: male and female, young and old, black and white.
First, Cloninger looked at how well the individual questions of the self-transcendence subscales
hung together. The TCI contains 33 questions about self-transcendence: 11 for self-forgetfulness,
9 for transpersonal identification, and 13 for mysticism. To test for coherence, Cloninger
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analyzed how well people’s answers to questions from the same subscale went together. For
example, when testing for mysticism coherence, he asked whether those fascinated by the
unexplained also sometimes think they have a “sixth sense.” And when studying the coherence
of self-forgetfulness, he asked whether people who often lose track of time are also frequently
considered absentminded.
The answer to the question of whether or not these questions had coherence was a resounding
yes. The reliability coefficients for each of the three subscales of self-transcendence were greater
than 75. That means that all of the answers to the individual questions within each subscale had a
far greater than random chance of hanging together. This part of the test was like asking people
what their weight is and then actually weighing them on a scale; the answers were not exactly the
same but were very close.
Next Cloninger turned to the three components that make up self-transcendence. Do they also
cohere? In other words, do people who normally experience self-forgetfulness also score high for
mysticism and transpersonal identification? Again the answer was a resounding yes. All of the
intercorrelations were greater than 50, a highly significant degree of relatedness. (Correlations
are measures of the relationship between variables. For the purposes of this book, the
correlations are given on a scale of 0 to 100, where 0 means no relationship exists and 100
signifies an exact correspondence.)
Even more impressive, when factor analysis was applied to the entire TCI, the three subscales
of self-transcendence were clearly separate from all other temperament and character traits. They
formed their own distinctive coherence. In other words, self-transcendence is as distinct from
other parts of personality as eye and hair coloration are from size.
These mathematical results show that there’s something fundamentally similar about the three
components of self-trancendence—self-forgetfulness, transpersonal identification, and
mysticism. Whatever it is that causes one of these traits to score higher or lower on the scale also
makes the other components score higher or lower. There’s a common root, a shared mechanism.
Of course, statistics alone can’t tell us what that common root is. It could be the result of a
gene. But it could equally well be the result of environment or culture. Math can tell us whether
things hang together but not the reason why. For that we need other tools.
Cloninger’s shopping-mall experiment had a practical implication: simplicity. One of the main
motivations behind using factor analysis is to allow scientists to measure a trait with just a few
questions instead of with many. To return to the example of measuring a person’s weight, we
might have first asked our subjects how much they weighed, then put them on a bathroom scale,
then checked again with a laboratory balance. That would give us three separate numbers that all
basically measure the same thing—three numbers to juggle when one would suffice. (Granted,
some people will be mistaken about their weight, but then some scales are not that accurate,
The same is true for spirituality. In subsequent experiments, in which we would be dealing with
a multiplicity of genes and other factors, it was vital to measure self-transcendence as frugally as
possible. Dealing with one number for the overall scale, or with three if using the subscales,
would be reasonable. Handling thirty-three numbers, one for each question on the questionnaire,
would have been impractical. Simple is good in science. Self-transcendence is, so far, the
simplest way we have to measure spirituality.
Hershey Heaven

Alfred Day Hershey, who won a Nobel Prize for showing that DNA is genetic information, had a
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simple definition of heaven: “To find one good experiment and then keep on repeating it over
and over again.”
His comment might seem silly, but it emphasizes the importance of replication in science,
especially in the behavioral sciences, where there always is a certain degree of subjectivity due to
the very nature of the topic. Before starting my hunt for the genes that influence our tendency
toward spirituality, it was important to see if Cloninger’s shopping-mall results on selftranscendence could be repeated. Would self-transcendence hold up as a cohesive factor in other
To find out, we analyzed the results of 1,001 subjects who took the TCI in connection with
genetic studies conducted by the National Institutes of Health. Some of them were students I met
at George Mason University. The rest came from other colleges in the Washington, D.C., area or
were recruited through advertisements in local newspapers. They were young and old, male and
female, black, Hispanic, and white. Some were religious, while others were not. They were, by
and large, a pretty ordinary group of people, as we had hoped.
The first order of business was to check whether the individual questions used to construct the
three self-transcendence subscales hung together in our data as they had in Cloninger’s study.
Indeed they did. The reliability coefficients were 66 for self-forgetfulness, 71 for transpersonal
identification, and 80 for mysticism, all of which are quite respectable. If the various questions
were unrelated, the scores would have all been zero. One or two questions didn’t fit Cloninger’s
model, particularly the ones about self-forgetfulness, but they were in the minority.
Next we looked at the overall structure of self-transcendence. Did the three subscales hang
together? Was there coherence? Again the answer was a resounding yes. The interscale
correlations were all above 45, which is more than acceptable for this type of analysis. When we
tried to force the data into other types of models, they didn’t fit nearly as well; the results of
Cloninger’s study were confirmed.
The corollary to Hershey’s definition of heaven is “There’s no such thing as too much of a
good thing.” We performed an additional factor analysis of self-transcendence on 387 subjects
for whom we had TCI data but not genotypes. Once again, self-transcendence stood out in terms
of its coherence. It didn’t matter which subjects we looked at or how we cranked the numbers.
The answer came out the same every time.
A Woman’s Place

Our reason for confirming the validity of the self-transcendence scale was that we wanted to
measure individual differences in spirituality and correlate them with genes. It was also
important, however, to know if there were any group differences in the scale, because these
would complicate and possibly compromise the genetic analysis. Our database of 1,388 subjects
allowed us to examine the relationship between self-transcendence and three potentially
important demographic variables: race, age, and gender.
There were no significant differences in self-transcendence among different racial and ethnic
categories. Although Americans of European, African, Hispanic, and Asian descent have varying
religious traditions, their scores on the spirituality scale were all very similar.
There were also no consistent connections between one’s age and self-transcendence. This was
initially surprising, since Cloninger has speculated that self-transcendence is a maturational trait.
(Nonetheless, his data show a similar lack of correlation.) Old and young alike have the capacity
to be spiritual.
There was, however, a gender difference. Women scored 18 percent higher on self******ebook converter DEMO Watermarks*******

transcendence than men. The difference was significant for both the overall scale and each
subscale, and it held true regardless of age, race, and ethnicity.
Although gender is statistically related to many different personality traits, the effect on selftranscendence is particularly strong. The reason for this is unknown. A statistical analysis
showed that the higher scores of women could not be accounted for by any of the other
personality factors we measured. It might be something to do with the fact that women are more
willing to express their feelings than men, or perhaps there’s something about our society that
brings out the spiritual in women. Or it might have something to do with their genes—a
possibility we would later have a chance to test experimentally.
Not a Factor by Any Other Name

There are only so many fundamental personality characteristics that distinguish one person from
the next. Many of them, like extroversion versus introversion, have been recognized for
centuries. Nevertheless, each psychologist who develops a new system for personality
classification has a seemingly irresistible tendency to rename each of the traits they “discover.”
It’s only human to seek recognition, of course, but it can get confusing for those of us who study
such things.
Cloninger is not immune to this tendency to rename things. The personality trait he calls “harm
avoidance,” for example, is basically the same as the trait Hans Eysenck termed “neuroticism,”
which in turn is virtually identical to what Raymond Catell called “anxiety.” All three
descriptions are based on related aspects of negative emotionality, such as worry, depression, and
shyness. More important, all three traits correlate strongly when the Cloninger, Eysenck, and
Catell questionnaires are administered to the same individuals.
Could self-transcendence, we wondered, be such a trait: an old trait under a new name? It
didn’t appear to be like anything else in the personality literature, but looks can be deceiving. A
better test would be to administer several different personality inventories to the same subjects
and then check whether self-transcendence is closely related to any previously described traits.
Fortunately, we had given almost all of our subjects two other personality tests as well: the
NEO and the 16PF. The NEO breaks down personality into five basic traits called neuroticism,
extroversion, openness, agreeableness, and conscientiousness. It’s a widely used inventory that
has been tested and validated in many different populations from around the world. The 16PF is
an older test, devised by Raymond Catell, that envisions personality in terms of sixteen basic
traits that make up five higher groupings: extroversion, anxiety, independence, toughmindedness, and control.
We found that none of the factors or traits previously identified were the same as selftranscendence. Our statistical analysis clearly showed that both the overall scale and the three
subscales of self-transcendence are unique. They are not contained in either of the other two
personality inventories. The only possible exception was the openness factor, which contains a
measure of imagination that is similar to mysticism. But even when all of the factors from the
NEO were used to predict a person’s self-transcendence score, the overall accuracy was less than
25 percent.
A Unique Trait

I apologize for all this number crunching, but it’s a necessary stepping-stone in understanding
the origins and the meaning of spirituality. What it shows is that spirituality, as measured by the
yardstick of self-transcendence, really is a unique trait, not just a personality quirk.
This is important, because many nonbelievers see spirituality as nothing but an expression of
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underlying insecurity—a fear of death, for example. But if that were the case, we would have
found a strong correlation between self-transcendence and measures of anxiety. We did not.
Others see spiritual practices such as meditation as nothing more than an attempt to stimulate a
jaded mind—a sort of safe form of mind alteration, similar to drug use. If that were true, we
would have found a strong association between self-transcendence and the personality traits of
novelty and thrill seeking. But again, we did not.
Although statistics can’t tell us what spirituality is or is not, or where it comes from, it can help
to measure spirituality in individuals and confirm its uniqueness. In a study of the connection
between genes and spirituality, that’s a good place to start.

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An Inherited

I myself believe that the evidence for God
lies primarily in inner personal experiences.
—William James

Unlike most young children, Jane and Rose loved going to mass, not just on Sunday but during
the week as well. They both decided as teenagers to devote their lives to the church and took
their vows together. Today, Sister Jane Frances and Sister Rose Marie are nuns at the same
convent in Akron, Ohio. In addition to their mutual interest in God and spirituality, Jane and
Rose have one other important similarity: their DNA. They are identical twins—the product of
the same fertilized egg.
Twins, especially identical ones like Jane and Rose, are fascinating. There is something
mysterious and alluring about people who look and sound identical.
But identical twins are more than curiosities. Because they share identical DNA, for scientists
they offer a way to dissect the role of genes and environment in complex human characteristics
like spirituality.
There are plenty of anecdotes about spiritually inclined twins such as Jane and Rose. One need
only visit the annual twins convention held each August in Twinsville, Ohio, to hear them by the
score. But are such stories the exception or the rule? How much of spirituality is inherited, and
how much is environmental?
Galton’s Legacy

The first scientist to recognize the potential of twins to answer quantitative questions about the
origins of behavior was Sir Francis Galton, a nineteenth-century English scientist who was a
cousin of Darwin. A child prodigy, adult polymath, explorer, geographer, statistician, and
psychologist, Galton is best remembered for originating the twin experiment that has been the
mainstay of behavior genetics to this day.
The main use of twins in behavior genetics research is to determine heritability, which is
defined as the percentage of variation in a behavior that is due to genetic differences. Heritability
can be most directly measured by comparing identical twins who were separated at birth and
raised apart. Because such twins have the same genes but are raised in different environments,
the extent to which they are similar to each other is a direct approximation of heritability. The
degree of similarity can be calculated as a correlation.
Unfortunately, there is a serious problem in studying identical twins separated at birth. There
just aren’t enough of them. Fewer than two hundred pairs are known in the entire United States,
and the number is getting smaller all the time, as it is now customary for twins to be adopted
together. The alternative for research purposes is to compare identical and fraternal twin pairs
who were reared together. Since fraternal twins, like ordinary siblings, share only half of their
genes, they should be less similar to each other than identical twins to the extent that genes are
important. Although twins reared together share the same environment, their environment can be
subtracted from the equation, since it’s the same regardless of zygosity—that is, whether the
twins develop from the same or different eggs. By comparing the correlations for the two types
of twins, fraternal and identical, it is possible to calculate how much of the individual differences
in a trait is due to genes and how much is due to growing up in the same or different households.
Galton invented the twin method of research long before anybody knew what genes were or
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how they worked. In fact, he didn’t even know why some twins appeared so similar and others
did not. But he guessed—correctly, as we now know—that it was because the identical twins had
the same inherited makeup, whereas the nonidentical twins were like ordinary brothers and
sisters. Galton therefore reasoned that “their history affords a means of distinguishing between
the effects of tendencies received at birth, or those that were imposed by their circumstances of
their after lives; in other words, between the effects of nature and nurture.”
Galton used his new twin method to examine many different aspects of human development,
health, and behavior, including toothaches, various diseases, personality, and life events. He even
explored whether or not dogs can smell the difference between twins.
Galton also was fascinated by spirituality and religion. He was the first modern scientist to try
to objectively study the efficacy of prayer and belief. To do so, he compared well-known
theologians and clergy to other eminent men. He found that the life spans of the clergy were no
longer and their illnesses no less frequent or severe than those of the laypeople.
The one thing that Galton did not do was to combine his interest in twins with his curiosity
about spirituality to explore whether or not belief has an inherited component. To ask the
question properly, he would have needed both an appropriate measuring stick and a sizable
collection of twins who had been reared apart. Those two elements didn’t coalesce until nearly a
century later in the American Midwest.
The Minnesota Experiment

Realizing the potential importance of twins reared apart for behavior research, twenty years ago a
group of scientists at the University of Minnesota began to systematically track down pairs who
had been separated at birth for one reason or another. Some of these twins had been reunited in
early adulthood; others did not even know they had a twin until middle age or later. Some twins
met by complete accident, such as the two men who ran into each other at a gay bar; others had
spent years looking for each other. Although there were pairs who were reared in quite similar
environments, in some cases by relatives, there were others who were brought up under
strikingly different circumstances. Oscar Stohr and Jack Yufe, for example, were raised in
different countries and disparate religions—Oscar as a Catholic in a small German-Czech border
town, where he joined a Hitler Youth group, Jack as a Jew in Trinidad, Venezuela, and then
Israel, where he lived in a kibbutz on the Sea of Galilee.
Although separated identical twin pairs are few and far between, the Minnesota scientists
eventually accumulated enough pairs to begin to ask quantitative questions about complex
human characteristics. In the first published study of its kind, the researchers examined 53 pairs
of identical twins and 31 pairs of fraternal twins, all reared apart, for five different scales of
religiousness. The emphasis of the study was on the sorts of orthodox values, beliefs, and
practices that are promoted by typical organized religions. Some of the scales looked at how
important religious faith was to the twins’ lives. Others asked how much of their leisure time
they spent in religious activities, such as attending services or working for their church or
synagogue. There were questions about interest in religious occupations, such as working as a
priest, minister, rabbi, or missionary; others tapped into particular tenets, such as belief in God.
The results of their study were consistent. For every scale examined, genes seemed to play an
important part. The calculated heritabilities were all between 41 and 52 percent, meaning that
genes were responsible for roughly half of the variation in religiousness from one twin to the
next. In other words, the study seemed to suggest that at least part of the reason people believe
that religion can help to answer life’s questions is their DNA.
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Although this first study provided fascinating new information about religiousness, it didn’t
really address one’s inherent spirituality. No measure of spirituality, such as the selftranscendence scale, was included in the analysis. In fact, little attention was given to people’s
underlying motivations and feelings. In a second study, however, the Minnesota researchers did
ask about religious motivation—about the reasons that people become religious—which is at
least closer to spirituality.
The Minnesota researchers analyzed religious motivation by using a questionnaire that
distinguishes intrinsic from extrinsic religiousness. Intrinsically religious people live their
religion. They often feel the presence of God, they pray as often when they are alone as at their
place of worship, and they try to practice their beliefs in every aspect of their lives. Extrinsically
religious people go to church or synagogue to see their friends or make new ones; they are even
willing at times to suppress their religious beliefs to impress others. Intrinsic and extrinsic
religiousness are unrelated; the correlation between the two scales is zero.
When the twin data was analyzed, the results for extrinsic religiousness were ambiguous. There
was a significant correlation for identical twins raised apart, suggesting that genes might play a
role. But the correlation for fraternal twins was actually greater, which doesn’t make any sense
for a heritable trait. The numbers were just too inconsistent to interpret.
The results for intrinsic religiousness were clearer. This measure, which comes closest to
spirituality in the Minnesota study, was found to be substantially genetic. The correlation for
identical twins was 37, about double the correlation of 20 for fraternal twins. When these
numbers were analyzed, the estimate for heritability came out to 43 percent. In other words,
nearly half of the reason that the twins felt religion helped them, spent time privately praying,
and had a sense of God’s presence was inherited. Since these twins were raised by different
parents, in different neighborhoods, and sometimes even in different religions, their similarities
seemed to be the result of their DNA rather than their environment. Something in their genes
helped to push them toward religion.
Self-Transcendence and Heritability

It’s difficult to imagine two scientists as dissimilar as Nicholas Martin and Lindon Eaves. Martin
is tall and lean, extroverted and loud, an Australian and proud of it. Eaves is short and plump, a
shy and soft-spoken Briton transplanted to the United States. Martin, who trained as a
psychologist, is an atheist. Eaves, a geneticist and mathematician, wears the collar of an
Anglican priest and preaches every Sunday. But there are two things that both men love: twins
and pushing the envelope.
Martin established the Australian Twin Registry, a large and systematic collection of identical
and fraternal twins that has been used to study everything from sexual orientation to freckling.
Eaves’s twin population, the Virginia 20,000, is even larger and has been the subject of hundreds
of research papers.
In 1999, Martin and Eaves teamed up with Australian scientist Katharine Kirk to pursue a new
topic for behavioral genetics: self-transcendence.
The sample was drawn from the Australian National Health and Medical Research Council
Twin Registry, a volunteer register begun in 1978 that has a total of about 25,000 pairs of twins
of either zygosity and various ages. The self-transcendence study focused on twins over 50 years
of age, who were mailed a health and lifestyle questionnaire. There were 3,116 replies, 1,279
from complete pairs and 558 from singles, which represented a response rate of 71 percent—a
typical result for a mail survey. The subjects had an average age of 61, with a range of 50 to 94
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years, and varied educational and socioeconomic backgrounds. There were about twice as many
women as men, which again is typical for this type of research.
Self-transcendence was assessed by fifteen questions selected from Cloninger’s TCI inventory.
Although each of the facets of self-transcendence was covered by the abbreviated test, there were
not enough items to determine individual scores for self-forgetfulness, mysticism, and
transpersonal identification.
Just as Cloninger found in St. Louis and we confirmed in Bethesda, the various questions about
self-forgetfulness, transpersonal identification, and mysticism all hung together in a coherent
fashion. Furthermore, the scale reliability and factor analytic statistics were virtually identical to
those found in the United States. (The one exception was the item “I love the blooming of
flowers in the spring as much as seeing an old friend again,” which for some unknown reason
didn’t fit in with the rest of the questions in Australia. Go figure.)
The twins were also asked several questions about their religious affiliation and church
attendance. This allowed the researchers to distinguish between spirituality, as measured by the
self-transcendence scale, and more traditional religiousness. The study included questions about
health, anxiety, depression, optimism, and various aspects of personality.
How did the researchers conduct their studies? First, they evaluated the data, using a
modeling technique that took into account three main sources of variation in selftranscendence: genetic influences, shared environmental influences, and unique
environmental influences. The first two factors make twins alike; the third makes them
different. The analysis indicated that genes are responsible for 48 percent of the variation in
self-transcendence in twins, both male and female. The remaining 52 percent of variance
was due to environmental factors for females. Age also had an effect; in males, it accounted
for 4 percent of variance. (Environmental factors accounted for the other 48 percent.)
The researchers also examined the data by a statistical technique called “multivariate
modeling.” Once again, they found that genes played an important role in selftranscendence. Using this analysis, the estimated heritabilities were 37 percent for men and
41 percent for women, which are similar to the numbers obtained in the first analysis. The
take-home lesson from the Martin and Eaves study was clear: Genes are a major factor in
self-transcendence. In other words, spirituality is, in good measure, an inherited trait.
To test the role of genes in self-transcendence, the scientists compared the similarity of
responses in identical twins to fraternal twins.
There was a striking difference.
The self-transcendence scores of identical twins were more alike by far than those of fraternal
twins. For males, the correlations came in at 40 in monozygotic twins, compared to 18 in
dizygotic twins; for females, the corresponding numbers were 49 and 26. In other words, the
ratio was close to 2 to 1 in both sexes, which is just what one would expect for a genetically
mediated trait, since identical twins are twice as similar at the DNA level as fraternal twins.
The Nature of Nurture

The main purpose of twin experiments is to determine to what extent genes are important for
different traits—to get at the nature side of the “nature versus nurture” question. But twin studies
are equally informative with regard to the role of the environment as a factor—the nurture side of
the story. Not only do they let us know that nurture is important, they can tell us what type of
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nurture makes a difference.
“The environment” is actually a bit of a misnomer, since the factors that affect who we become
are certainly not a single entity. The environment includes everything from the type of diaper
you wore as an infant and the weather on your third birthday to your parents’ income and the
amount of lead in your classroom paint. It’s the catechism you were taught in Sunday school and
the TV show you watched last night. The environment is anything and everything—biological,
physical, intellectual—that you didn’t inherit as DNA.
Behavioral scientists break down the environment into two major categories: shared and
unique. In twin studies, the shared environment consists of everything that both twins
experienced by growing up in the same household. This includes general parenting style, income
level, social class, schooling, and religious upbringing.
The unique environment is everything else. It includes each and every factor and experience
that twins do not share. If the twins have different schoolteachers, that’s a unique component of
the environment. If one of them gets measles and the other does not, that, too, is unique.
Is shared or unique environment more important in terms of spirituality? Twin data can be used
to answer this question. If the shared environment were important, for example, both identical
and fraternal twins would be more similar to each other than random individuals who grew up in
different households. Furthermore, the extent of correlation due to shared environment would not
be influenced by their genes, since both types of twins would have shared it to the same extent.
As a result, fraternal twins would resemble each other more than expected on the basis of their
50 percent genetic similarity.
By contrast, suppose that the unique environment were the critical factor. If that were true,
fraternal twins and identical twins would be less similar to each other, rather than more similar.
Whatever similarity existed between twins would be due to genes plus shared environment, and
whatever part of that similarity is inherited would be twice as great in identical twins as in
fraternal twins. By combining these two facts, it is easy to derive equations that parse out the
separate contributions of genes, shared environment, and unique environment.
An important assumption in this calculation is that identical and fraternal twins share
environment to the same extent. Critics of twin experiments often question this assertion,
pointing to anecdotes of identical twins being treated very similarly. Fortunately, it’s possible to
test the “equal environments assumption,” as it’s known, by an experiment. The trick is to take
advantage of the fact that some parents mistake identical twins for fraternal and vice versa. When
such “pseudo-identical” and “pseudo-fraternal” twins are compared with real identical and
fraternal twins, there’s no difference. It doesn’t make any difference whether parents think that
the twins are genetically the same or not. It only matters whether they have the same DNA.
When this type of mathematical analysis was applied to the twin data on self-transcendence, the
result was clear. What is important is unique environment. In the univariate statistical model, the
unique environment accounted for 48 to 52 percent of variance in men and women, respectively,
and shared environment accounted for zero. In the multivariate model, unique environment
accounted for 42 to 50 percent of variance, and shared environment remained insignificant.
This was a surprising result. The implication is that spirituality, at least as measured by selftranscendence, doesn’t result from outside influences. Contrary to what many people might
believe, children don’t learn to be spiritual from their parents, teachers, priests, imams, ministers,
or rabbis, nor from their culture or society. All of these influences are equally shared by identical
and fraternal twins who are raised together, and yet the two types of twins are strikingly
dissimilar in the extent to which they correlate for self-transcendence. In other words, William
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James was right: Spirituality comes from within. The kernel must be there from the start. It must
be part of their genes.
The Difference Between Spirituality
and Religiousness

When Galton first studied twins more than a century ago, the results were so striking that he
feared nobody would believe him. “My only fear is that my evidence seems to prove too much
and may be discredited on that account, as it seems contrary to all experience that nurture should
go for so little,” he wrote.
The twin researchers in Minnesota and Australia had the same concern. Their results seemed
almost too good to be true. It seemed that everything they looked at was heavily genetic and that
the shared environment didn’t make a bit of difference. This appeared to be true not just for
religious motivations and self-transcendence, as in the studies described above, but also for such
basic traits as intelligence, personality, activity level, mental disorders—including schizophrenia
and manic depression—and assorted behaviors ranging from cigarette smoking to petty
criminality. And then there were the truly eerie similarities between the twins raised apart, like
those who gave their dogs the same name or used the same obscure brand of toothpaste.
Critics of behavior genetics were incredulous. Could there really be “a gene for” something as
idiosyncratic as one’s preference in dog names or brand of toothpaste? Perhaps, said the skeptics,
there was something fundamentally wrong with the whole twin approach. Maybe there was some
basic error in the methodology that made everything seem genetic even when it was not. And
why did the shared environment seem so unimportant? Perhaps twin experiments were
methodologically incapable of sensing the role of parents, teachers, and society.
The best way to refute the critics would be to use the twin method to look at a trait that was at
least partially learned—something that was influenced by culture as much as heredity. With that
idea in mind, Martin and Eaves decided to look at religious-service attendance in the same
sample of Australian twins whom they had studied for self-transcendence. Their reasoning was
that the frequency with which a person goes to church, synagogue, or mosque is more likely to
be learned than inherited, because it varies so much from one culture to the next. For example,
Australians go to church much less frequently than do Americans. About half of the folks down
under, compared to less than one-third of people in the States, attend rarely or never. And only 7
percent of Australians go to church more than once a week, whereas the number in America is
more than twice that. Since Australians and Americans have the same genes, church attendance
is more likely to be learned than inherited.
That is exactly what analysis of the Australian twin data showed. The main factor that caused
twins to be similar to each other for church attendance was shared environment, not genes. The
correlations were almost identical for identical and fraternal twins, allowing the researchers to
conclude that shared environment was responsible for 43 percent of the variance in both males
and females; the remaining variation was due to a mixture of unique environment and a limited
genetic component.
Could the same genes be responsible for the inherited components of religious attendance and
spirituality in women? To test that possibility, the researchers looked at the correlations between
church attendance in one twin and self-transcendence in the co-twin. If the same genes were
involved in both traits, these cross-twin, cross-trait correlations would be stronger in identical
than in fraternal twins.
This was not the case for church attendance and self-transcendence. They aren’t linked at all.
Both the within-twin and across-twin correlations were small and were completely independent
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of zygosity. Whatever the genes are for spirituality, they don’t have any effect on how often
people go to church.
Maslow, Cloninger, and many others before them and since have argued that spirituality and
religiousness are fundamentally different. The twin studies, by looking quantitatively at both
qualities in a single population, strongly support the distinction. More important, they tell us
something about why they differ. Religiousness, as measured by church attendance, is learned in
the classical sense—from parents, teachers, religious leaders, and peers. People go to church or
mosque or temple because that’s what they were told to do. Spirituality, as measured by selftranscendence, is more innate. It comes from within, not from without. Of course, spirituality has
to be developed, just like any other talent. But the evidence suggests the predisposition is there
from the beginning.
Brothers and Sisters

Although studies of identical twins like Jane and Rose play an important role in figuring out
whether heredity is important for a trait, they’re useless for actually isolating the genes. The
DNA of identical twins is too similar to be informative in mapping experiments. To properly
conduct such studies, what’s needed are fraternal twins or siblings—individuals different enough
for genetic localization (since 50 percent of their DNA variations are distinct), but similar
enough to compare (since the other half of their DNA variations are identical). Siblings also
usually are raised in the same environment.
Since siblings are much more common than fraternal twins, we focused our attention on them.
As I described in the previous chapter, we recruited pairs of brothers and sisters from local
colleges and the community, took some cells to isolate DNA, and gave them the TCI to measure
self-transcendence. Before going any further, though, we needed to confirm the twin results
about heritability in our population.
The logic was that siblings, who are 50 percent genetically related, should have similar scores
for self-transcendence if it is indeed a heritable trait. If sibling scores were not related—if the
correlation were zero—then self-transcendence could not be heritable in our population. It is
important to emphasize that this test cannot prove heritability, since a positive correlation could,
in principle, be due to genes, shared environment, or a combination of both. But it can be used to
double-check that the population is consistent with previous studies of heritability, since a
negative result would mean genes could not be involved.
When we examined our group of 447 pairs of siblings, they indeed scored similarly for selftranscendence. The correlation was 37, which was as high or higher than expected from the
heritability calculated for Australian twins by Martin and Eaves.
The sibling correlation for self-transcendence was true regardless of sex, age, or race. Brothers
were like brothers, sisters like sisters. Older siblings were as alike as those still in college.
Regardless of race or culture, if one member of a pair scored particularly high or low for selftranscendence, his or her sibling usually did, too.
These results don’t mean that siblings are always the same. There are plenty of exceptions,
which is to be expected, since although siblings share 50 percent of their DNA variations, the
other 50 percent are different. And even though siblings grow up in the same shared
environment, their unique environment is just that—unique.
Sometimes the differences between siblings are striking. Tenkai, the Zen monk I describe in
Chapter One, has a brother who is an executive in a manufacturing firm in Germany. He thinks
spirituality is nonsense and laughs when Tenkai explains why he meditates. He has little interest
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in social justice or nature; he hates the Green Party with a passion. These two siblings couldn’t
be farther apart on the self-transcendence scale.
But there are also siblings like Gloria and Louise. I met them one fine spring Sunday morning
at Mount Gilead Baptist, a predominantly African American church located a few blocks from
my house in a gentrified neighborhood of Washington, D.C., that is now predominantly white. In
attendance were ostrich-plumed women of a certain age with their grandchildren in tow, whitegarbed church ladies with their dark-suited husbands, a sprinkling of young couples.
Gloria has been going to this church her entire life. She attended Sunday school when her
parents still lived in the neighborhood, she was married here, and now she’s a deaconess and a
good friend to most all of the parishioners. But her devotion to the church goes beyond the
social. She prays regularly—not just in the morning or evening, but repeatedly through the day.
She has found Christ—not once or twice but over and over. She is a believer.
This morning it is Gloria’s duty to read the announcements from the pulpit. She exhorts her
flock to publicize an upcoming church picnic, saying, “The best way to get the news out is to
telephone, telegraph, or tell-a-woman.” With the last comment she looks directly at a woman in
the audience and gives a hearty chuckle.
The woman is her sister, Louise, the black sheep of the family. Louise never liked Sunday
school. She didn’t enjoy regular school, either, and dropped out when she became pregnant with
the first of four children at age sixteen. For the next twenty-five years, Louise struggled with
alcohol, drugs, and a string of “good-for-nothing” men who seemed to be mostly interested in
her welfare checks.
Then, as the result of a twelve-step program, Louise found God. She discovered that faith in a
higher power was the one thing that could keep her off drugs and alcohol, a