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Is the “born gay” theory accurate?

The majority of these studies are so far-fetched that few people give them much credence, except those who turn to the popular media for their “truth.” But, as Proverbs 18: 17 says, “The first to present his case seems right, till another comes forward and questions him.” With that in mind, let’s consider the validity of these studies.

Simon LeVay and the INAH-3

Neuroanatomic (or brain structure) research hoping to secure a biological determinant to homosexuality seemed to reach its zenith in 1991 when Simon LeVay published “A Difference in Hypothalamic Structure Between Heterosexual and Homosexual Men” in the respected journal Science. He studied the brains of 41 corpses, including 6 women, 19 homosexual men, and 16 men presumed to be heterosexual. LeVay examined a portion of the hypothalamus (INAH-3), which is a small segment of the brain structure. He reported that the INAH-3 was more than twice as large in the heterosexual men as in the women and twice as large in heterosexual men as in the homosexual ones. What did LeVay deduce from all of this? That “sexual orientation has a biological substrate” because if the brains of homosexual men were closer in size to the brains of women than the brains of heterosexual men, then of course gay men must be more biologically like women.

Even the simplest analysis of LeVay’s methodology quickly uncovers numerous methodological errors. LeVay himself admits that his most glaring problem is that all 19 of the subjects identified as homosexual had died from AIDS complications. Is it possible, then, that the size difference in their hypothalamuses was caused by their illness rather than their homosexuality?

In fact, that’s exactly what Dr. William Byne suggested. He found that LeVay 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. Thus, it is possible that the effects on the size of the INAH-3 that he attributed to sexual orientation were actually caused by the hormonal abnormalities associated with AIDS.

But we don’t have to take anyone else’s word for what LeVay’s research doesn’t prove; he’s already spoken quite clearly on the subject. “I did not prove that homosexuality is genetic, or find a genetic cause for being gay,” he admitted. “I didn’t show that gay men are born that way, the common mistake people make in interpreting my work. Nor did I locate a gay center in the brain.” Even more emphatically, LeVay states that, “time and again I have been described as someone who ‘proved that homosexuality is genetic’… I did not.”

The Bailey and Pillard Twin Studies

Another widely cited “proof” of homosexuality’s genetic link is often attributed to the Bailey and Pillard twin studies. This research was conducted using pairs of brothers — identical twins, nonidentical twins, biological brothers, and adopted brothers — at least one of whom was gay. Here are the results:

  • 52% of the time, both identical twins were homosexual
  • 22% of the time, both nonidentical or fraternal twins were homosexual
  • 9.2% of the time, both non-twin brothers were homosexual
  • 10.5% of the time, both adoptive brothers were homosexual

Those statistics seem to point to a genetic link — don’t they? Not to N.E. Whitehead, Ph.D.:

Identical twins have identical genes. If homosexuality was a biological condition produced inescapably by the genes (e.g. eye color), then if one identical twin was homosexual, in 100% of the cases his brother would be too… Genes are responsible for an indirect influence, but on average, they do not force people into homosexuality. This conclusion has been well known in the scientific community for a few decades but has not reached the general public. Indeed, the public increasingly believes the opposite.

In the same vein, if homosexuality were to truly have genetic links, the group that should show the least amount of homosexual conformity would be the brothers with completely unrelated genes — the adoptive sets. Yet this isn’t the case.

Dean Hamer and the X Chromosome

The last study that has advanced the “born gay” theory was released in 1993 and touched off a national media storm, including a Time magazine cover story called “Born Gay: Science Finds a Genetic Link.”

What was all the hubbub about? Author Steven Rose remembers:

Back in 1993 a euphoric press release announced the publication in America’s leading scientific journal, Science, of a paper reporting the discovery of a “gay gene.” Hamer, the senior author both of that paper and Living with Our Genes… works at the U.S. government’s National Cancer Institute, but the relevance of his genetic study of 40 pairs of gay brothers to cancer research is obscure. What Hamer and his colleagues actually reported was relatively modest; that these 40 gay siblings shared a common genetic marker, a region of their X-chromosome, inherited from their mother, called Xq28. No actual gene has been discovered, merely a genetic association, and what, if anything, such a gene might have to do with the brothers’ sexual orientation was equally unclear. But this didn’t prevent the press release labelling the discovery as “gay gene” and speculating on its ethical consequences. Gay men wore T-shirts thanking Mom for Xq28.

Hamer had indeed claimed that homosexuality could be linked to findings on the X chromosome. He found that out of 40 pairs of homosexual brothers, 33 (83 percent) received the same sequence on five genetic markers. Like the two previous studies, anyone willing or needing to accept a genetic link to homosexuality would rejoice in these findings.

But scientists — men and women concerned with facts, not emotion or lifestyle advocacy — had a much different reaction. Whitehead pointed out the study lacked a control group from the general population, noting that if the same sequence from the X chromosome that appeared in the homosexual men also appears in the general population of heterosexual men, then the gene is insignificant. Hamer also did not test the heterosexual brothers of the homosexual men to see if they had the gene, but some of the data from those heterosexual brothers did indicate that they had the identical gene sequence. Another conspicuous flaw in Hamer’s study is that seven of the pairs of homosexuals did not have the needed gene sequence at all.

Perhaps most telling, though, are Hamer’s own words about his study: “The pedigree study failed to produce what we originally hoped to find: simple Mendelian inheritance. In fact, we never found a single family in which homosexuality was distributed in the obvious sort of pattern.”

The simplest amount of questioning on the part of one seeking truth regarding these studies inevitably produces the same fruit: no evidence of a genetic link to homosexuality.

MIKE HALEY
101 Frequently Asked Questions About Homosexuality (2004) Harvest House: Eugene, Oregon

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