"Do Our Genes Influence Behavior? Why We Want to Think They Do"
Chronicle of Higher Education, November 26, 2004
A few weeks ago I was hurrying past a newsstand in Grand Central Station when the cover of the latest issue of Time stopped me short. Superimposed on a painting of a blue-skinned, red-lipped woman, her hands clasped in prayer, were the words "The God Gene." The article within reported that in a new book with that title, the geneticist Dean Hamer had traced belief in God to a specific gene. "Does our DNA compel us to seek a higher power?" Time asked.
The article left me pondering a different question: Given the track record of behavioral geneticists in general, and Dean Hamer in particular, why does anyone still take their claims seriously?
Behavioral genetics, which attempts to explain what we are and do in genetic terms, began with the English polymath Francis Galton, who in 1883 coined the term "eugenics" to refer to his proposal that humanity improve itself through judicious breeding. Galton's measurements of the physical and mental characteristics of various groups had convinced him that upper-class gentlemen like himself were innately smarter than poor white men, let alone "inferior races" like Africans. On a trip to Africa, however, Galton was mightily impressed with the physical endowments of Hottentot women, whose bodies he measured from afar with a sextant because he was too timorous to approach them.
Galton's ideas were carried forward in the United States by Charles Davenport, who directed biological research at the prestigious Cold Spring Harbor Laboratory on Long Island around the turn of the last century. Davenport believed in the heritability of traits like pauperism, shiftlessness, and the ability to be a naval officer. The latter, he asserted, was composed of subtraits for thalassophilia, or love of the sea, and hyperkineticism, or wanderlust. Noting the paucity of female naval officers, Davenport concluded that the naval-officer trait must be unique to males.
Until recently behavioral geneticists could only estimate the contribution of genes to traits like musicality or criminality, based on inheritance patterns within families and other groups. But in the 1980s advances in biotechnology allowed researchers to pinpoint specific genes responsible for such highly heritable diseases as cystic fibrosis, Huntington's chorea, and early-onset breast cancer. Those successes emboldened behavioral geneticists to search for the genes underlying much more complex ailments, personality traits, and behaviors.
Over the past 15 years or so, researchers have announced the discovery of "genes for" attention-deficit disorder, obsessive-compulsive disorder, manic depression, schizophrenia, autism, dyslexia, alcoholism, heroin addiction, high IQ, male homosexuality, sadness, extroversion, introversion, novelty seeking, impulsivity, violent aggression, anxiety, anorexia, seasonal affective disorder, and pathological gambling. So far, not one of those claims has been confirmed. That should not be surprising, given that complex traits and disorders are almost certainly caused by many different genes interacting with many different environmental factors.
Moreover, the standard methodology of behavioral genetics results in many false positives. Researchers select a group of people who share a trait and start searching for a gene that occurs not necessarily in everybody in that group and in nobody outside it, but just more often in that group than in a control group. Critics point out that if you look at enough genes, you will almost inevitably find one that meets those criteria simply through chance.
Behavioral geneticists keep churning out new "discoveries" nonetheless, and the media keep hyping them. No researcher has attracted more media attention than Dean Hamer, chief of the Section on Gene Structure and Regulation in the Laboratory of Biochemistry at the National Cancer Institute.
In 1993, Hamer and four colleagues claimed in Science that their study of 40 pairs of gay brothers had turned up genetic markers in chromosome X associated with homosexuality. The announcement made headlines worldwide, and the resulting book, The Science of Desire (Simon and Schuster, 1994), which Hamer wrote with the journalist Peter Copeland, was one of The New York Times's "Notable Books" of 1994.
That same year, according to a report in the Chicago Tribune, one of the co-authors of his "gay-gene" paper accused him of improperly excluding data that did not support his conclusion. The charges triggered an investigation by the Office of Research Integrity of the Department of Health and Human Services that was quietly dropped several years later without any formal resolution. Meanwhile two other studies involving more subjects than Hamer had used found no evidence linking a gene in chromosome X to male homosexuality.
Compared to Hamer's original claim, those contradictory reports received virtually no media coverage. Indeed, in 1997 Discover lauded Hamer as a "big-gene hunter" leading the effort to ferret out "the genes that shape our individual personalities."
By then Hamer had, with co-authors, published two other papers linking specific genes to two different complex traits: novelty seeking, or thrill seeking, as many journalists described it; and harm avoidance, or neurosis. "Oedipus Schmoedipus," Time quipped in a story on the "neurosis gene." "The fault, Dear Sigmund, may be in our genes."
Two subsequent studies found no evidence for the novelty-seeking gene. The neurosis-gene report also remains unconfirmed.
Undeterred, Hamer contended in his 1998 book, Living with Our Genes (Doubleday), also written with Peter Copeland, that he and other researchers had demonstrated "beyond a doubt that genes are the single most important factor that distinguishes one person from another." He added that "whether anyone thinks it's a good idea or not, we soon will have the ability to change and manipulate human behavior through genetics." Hamer speculated that parents will be able to fine-tune children's genes so that they grow up healthier, smarter, happier, and blessed with more talent for, say, mathematics, music, or cooking. Such designer-baby predictions, which have been echoed by other prominent geneticists, are laughable, given the track record of behavioral genetics.
Incredibly, the "God gene" is based on even flimsier evidence than Hamer's previous claims. This work began in the late 1990s, when Hamer assembled 1,000 subjects for a study of the genetics of nicotine addiction. Participants filled out a detailed questionnaire, one section of which attempted to measure their "self-transcendence" or "spirituality" by asking them to rate their feelings of connectedness with nature, absent-mindedness, and belief in extrasensory perception, among other characteristics. Hamer decided to search for genes that occurred more often in "spiritual" subjects, and he finally found one that accounted for roughly one percent of the variation in his participants' test scores.
In The God Gene, Hamer describes that result as hitting "pay dirt," and in a sense he did because, according to Publishers Weekly, he received a "mid-six-figure" advance to write his book. In Scientific American, the journalist Carl Zimmer quipped that Hamer should have called his book "A Gene That Accounts for Less Than One Percent of the Variance Found in Scores on Psychological Questionnaires Designed to Measure a Factor called Self-Transcendence, Which Can Signify Everything From Belonging to the Green Party to Believing in ESP, According to One Unpublished, Unreplicated Study." But The God Gene has received positive coverage not only in Time but also in The New York Times and The Washington Post, both of which found his science "persuasive."
So back to my original question: Why are the claims of Hamer and other behavioral geneticists still taken seriously? The effort to identify the genetic basis of character traits was once associated with eugenics, social Darwinism, Nazism, and other right-wing, racist ideologies. To some extent it still is, most obviously in works like The Bell Curve, the 1994 bestseller in which Richard J. Herrnstein and Charles Murray argued that blacks score lower than whites on IQ tests not because they are culturally disadvantaged but because they are innately less intelligent.
But other genetic theories have surprisingly broad appeal. Some gay activists, for example, support the effort to find a genetic basis for homosexuality; their hope is that society will become more tolerant of homosexuality if it is shown to stem from genes rather than conscious choice. Hamer, who is gay, has voiced that hope. Similarly, some advocates for the mentally ill have embraced theories that blame schizophrenia, manic depression, alcoholism, and other disorders on genes rather than on the character flaws of patients or their parents,. And in fact rigorous inheritance studies (yes, they do exist) suggest that some mental disorders are at least partially innate.
As a journalist, I also understand all too well the media's fondness for discoveries of a gene for [fill in the blank]. We science reporters occupy a humble niche in the vast news and entertainment industry; even someone as experienced and talented as Jeffrey Kluger, who wrote the "God gene" story for Time, must compete fiercely for editors’ and readers' attention. Discoveries of a "gay gene" or "God gene" are classic examples of what science writers call "gee-whiz" stories; the science is easy to understand, and its philosophical and social implications are titillating. Call it "gene-whiz" science.
Gene-whiz science also appeals to our profound desire for self-knowledge and self-improvement. That desire is in some respects admirable and even noble, but it can also get us into trouble. Science is never more dangerous than when it tells us who we are or who we should be. Nazi Germany and the Soviet Union, after all, were both inspired by supposedly scientific theories of human nature.
There are responsible behavioral geneticists, but they rarely make headlines, because they emphasize the uncertainties of their research. Someday behavioral genetics may yield profound and even useful truths about why we do what we do, but for now we should view the grandiose claims of researchers like Hamer skeptically. Of course, some might say that that's just the anti-genetics gene in me talking.
Houghton Mifflin, January 2003.
With Reverend Frank Geer. Edited and with an Introduction by Robert Hutchinson. Brown Trout, 2002. Royalties go to Help the Afghan Children Inc.
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