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Born or Bred? The Debate Over the Cause Of Homosexuality 6/1/2000 The debate over homosexual "rights" often spirals into a discussion over whether homosexuality is a learned behavior or a genetic trait. Many homosexual activists insist that they cannot help their sexual behavior. They have argued that scientists have "proven" homosexuality is biological through studies that link sexual orientation to everything from differences in portions of the brain,1,2 to genes,3 finger length4 and inner ear differences.5 With all this scrambling for scientific evidence, one would think the issue has been settled. But if we take an intellectually honest look at the research, we may find more questions raised than answered. The Hypothalamus The first frenzy of this trend erupted in 1991 when Simon LeVay published a study in Science. His study noted a difference in a brain structure called the hypothalamus when evaluating homosexual and heterosexual men. LeVay found that in the specimens he studied, the hypothalamus was generally larger in heterosexual men than in homosexual men. Therefore he concluded that these findings "suggest that sexual orientation has a biologic substrate."6 While LeVay’s study hit the media with a splash that rippled from coast to coast, it was anything but conclusive. An analysis of the study and its methodology reveals some serious flaws. The first problem, which LeVay himself readily admits, is that all 19 of his homosexual subjects had died of complications associated with AIDS. Therefore the difference in the hypothalamus might well be attributed to the AIDS rather than homosexuality. LeVay attempted to compensate for the weakness by including a few heterosexuals who died of AIDS complications in the heterosexual sample. However, LeVay did not know for sure whether all subjects in his heterosexual sample were indeed heterosexual; all of these subjects were simply "presumed heterosexual." Moreover, Dr. William Byne argued in Scientific American that "[LeVay’s] inclusion of a few brains from heterosexual men with AIDS did not adequately address the fact that at the time of death virtually all men with AIDS have decreased testosterone levels as the result of the disease itself or the side effects of particular treatments. ¼ Thus it is possible that the effects on the size of the INAH3 [hypothalamus] that he attributed to sexual orientation were actually caused by the hormonal abnormalities associated with AIDS."7 Another weakness of LeVay’s study is that even in his sample there were "exceptions"—that is, there were some homosexuals who had larger hypothalamus structures than some of the heterosexuals examined. Even LeVay admits that these exceptions "hint at the possibility that sexual orientation, although an important variable, may not be the sole determinant of INAH3 [hypothalamus] size."8 LeVay is an open homosexual, and his interview with Newsweek suggests he had an agenda from the outset. LeVay lost his gay partner to AIDS, an event that made him re-evaluate what he was doing with his life. As a result, he took on this project. LeVay believes America must be convinced that homosexuality is determined biologically. "It’s important to educate society," he told Newsweek. "I think this issue does affect religious and legal attitudes."9 Since LeVay released his study, other researchers have found that brain structures can change as a result of life experiences. In 1997, University of California at Berkeley psychologist Marc Breedlove released a study that showed that sexual activities of rats actually structurally changed aspects of the brain at the base of the spinal chord. "These findings give us proof for what we theoretically know to be the case—that sexual experience can alter the structure of the brain, just as genes can alter it," Breedlove commented. "You can’t assume that because you find a structural difference in the brain, that it was caused by genes. You don’t know how it got there."10 Breedlove is not an activist out to prove homosexuality is not biological. In fact, he does believe a genetic component exists somewhere, but he, unlike LeVay, seems willing to take a more honest approach to research. The X Chromosome In 1993 a group of medical researchers at the National Cancer Institute, led by Dr. Dean H. Hamer, released a study that linked homosexuality to the X chromosome. While the study won a great deal of media attention, it also offered little proof of a biological link to homosexuality. Hamer’s results are often misunderstood. Many believe that the study found an identical sequence (Xq28) on the X chromosome of all homosexual brothers. In reality, what it found was matching sequences in each set of brothers who were both homosexual. Dr. Byne argues that in order to prove anything by this study, Hamer would have had to examine the Xq28 sequence of gay men’s heterosexual brothers. Hamer insisted that such an inclusion would have confounded his study. Byne responded, "In other words, inclusion of heterosexual brothers might have revealed that something other than genes is responsible for sexual orientation."11 Hamer’s motives are also questionable. Although his research is sponsored by the National Cancer Institute, his work has had little to do with cancer. This study alone took $419,000 of the institute’s taxpayer-backed funds, according to The Washington Times.12 One of Hamer’s researchers told the Times that homosexuality is "not the only thing we study," but it is "a primary focus of study." Hamer reportedly stated he has pushed for an Office of Gay and Lesbian Health inside the National Institutes of Health, and he testified in opposition to Colorado’s Amendment 2, which sought to keep homosexual activists from winning minority class status. Sen. Robert C. Smith (R-New Hampshire) accused the doctor of "actively pursu[ing] ¼ a gay agenda."13 Another fact that casts doubt on Hamer’s conclusions is that his study has not been replicated by other researchers, which would help to confirm his theory. In 1999, Drs. George Rice, Neil Risch and George Ebers published their findings in Science after attempting to replicate Hamer’s Xq28 study. Their conclusion: "We were not able to confirm evidence for an Xq28-linked locus underlying male homosexuality." Moreover, they added that when another group of researchers (Sanders, et al.) tried to replicate Hamer’s study, they too failed to find the genetic connection to homosexuality.14 The Twin Study Another study that has advanced the theory that homosexuality is a biological phenomenon is the famed "Twin Study" by J. Michael Bailey and Richard C. Pillard. Bailey and Pillard examined identical and fraternal twin brothers and adopted brothers in an effort to establish a genetic link to homosexuality. The study results yielded some statistics that seem to support the hypothesis and other statistics that appear to refute it. Fifty-two percent of the identical twins shared the same homosexual sexual orientation, while only 22 percent of fraternal twins fell into the same category. This finding appears to support the argument for biology, since identical twins share the same genes. However, the rate of non-twin conformity should mirror that of fraternal twins. In the Bailey and Pillard study, the rate was only 9.2 percent. And the rate in adopted—which, if the biological hypothesis were true, should have been even lower than non-twin brothers—was actually higher (11 percent).15 In his analysis of the medical evidence supporting a biological cause of homosexuality, Dr. Byne noted other twin studies. He wrote, "Without knowing what developmental experiences contribute to sexual orientation ¼ the effects of common genes and common environments are difficult to disentangle. Resolving this issue requires studies of twins raised apart."16 Other physicians have also criticized the study for overvaluing the genetic influence.17 Dr. Byne’s arguments might lead some activists to label him a "homophobe." He is, in reality, quite the contrary. Byne readily advocates societal acceptance of homosexuality, but nevertheless concludes, "Most of the links in the chain of reasoning from biology to social policy [regarding homosexuality], do not hold up under scrutiny."18 As a matter of fact, Bailey did conduct another study in 1999, published in the March 2000 issue of the Journal of Personality and Social Psychology, that revealed the genetic influence on homosexuality he supposedly found earlier may actually be less. He sent a questionnaire to the entire Australian Twin Registry. Only three pairs of identical male twins were both homosexual out of a total of 27 male identical twin pairs in which at least one was homosexual. Of the 16 fraternal male twins, in none of the pairs were both homosexual. Bailey found similar results for lesbians.19 Hormones The determination to find a biological link to homosexuality continued through the turn of the millennium, as researchers examined exposure to certain hormones as a biological cause of homosexuality. In 1998, researchers Dennis McFadden and Edward G. Pasanen published a study that evaluated the auditory systems of heterosexuals and homosexuals. Specifically the study considered differences in echo-like waveforms emitted from an inner ear structure of people with normal hearing. These waves are higher in women than in men, often attributed to the person’s exposure to androgen (a male hormone) in his or her early development as a fetus.20 The McFadden study found the level of these waveforms in the ears of self-acknowledged lesbian women ranged between those of men and those of heterosexual women. The researchers concluded that this evidence suggests that female homosexuality could be a result of increased exposure to the male hormone androgen in the womb (homosexual men did not show the same variation).21 The media eagerly jumped on this bandwagon, touting the evidence that homosexuality is indeed biological. But even the researchers themselves are not too quick to draw definitive conclusions. They caution that the results are only tentative. In the published study, they point out that exposure to "intense sounds, certain drugs, and other manipulations" can lower the level of these auditory waveforms. "Thus, it may be that something in the lifestyles of homosexual and bisexual females leads them to be exposed to one or more agents that have reduced the [waveforms], either temporarily or permanently."22 Moreover, even if the hearing differences were caused by an increased exposure to androgen in the womb, scientists would still be a far cry away from proving that this exposure is a cause of homosexuality—especially since the difference was not apparent in the male homosexual sample. In March 2000, yet another study on a biological link to homosexuality hit the media with fanfare. This time researchers weren’t looking at ears, but fingers. Scientists believe finger length indicates how much exposure a person had to androgen while in the womb. Typically, people’s index finger is slightly shorter than the ring finger—a difference that is seen more clearly on the right hand due to exposure to higher levels of androgen while the human is developing in the womb. In females, the ring finger and index finger are almost the same size, but in men the ring finger is generally shorter. In this study, Berkeley’s Dr. Breedlove, who had in 1997 shown how sexual activity can change brain structure, found that homosexual women’s finger length had a tendency to follow the male pattern. But again, the media was more eager than the researcher to draw definitive conclusions as to what this means. In fact, Breedlove told CNN, "There is no gene that forces a person to be straight or gay. … I believe there are many social and psychological, as well as biological, factors that make up sexual preference."23 Fact or Spin? Homosexual activists have been working to legitimize their sexual behavior for decades. Now they have found a strategy to win a foothold in America’s heart. "If homosexuality is biological, how can society condemn it?" they argue. Unfortunately, their "proof" is based on flawed studies and media spins. Science has yet to produce a conclusive study that shows homosexuality has a biological cause. As homosexual activists vie for legitimacy in American society, citizens and legislators would do well to avoid putting their confidence in political rhetoric and take some time to examine the facts. |
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