The Gay Gene: Assertions, Retractions, and Controversy

This web page was produced as an assignment for an undergraduate course at Davidson College.

Introduction:

Homosexuality and the rights of homosexuals are enormous issues in our society today. A scientific ‘breakthrough’ that proved the genetic predetermination of homosexuality would change society drastically. If science were able to ‘prove’ that sexual orientation was caused at the genetic level, discrimination against homosexuals must necessarily be viewed as unjust. On the other side of the coin, if sexual orientation could be determined in the fetus, in the future parents might elect to insert a heterosexual gene into their child or abort the child altogether. Although this grizzly scenario isn’t probable in the near future, it is not totally out of the realm of possibility – assuming a gene for homosexuality is found.
Over the years (from 1991 to the present) the story of the so-called ‘gay gene’ is one indicative of scientific experiments and conclusions molding themselves into media forces that then seem to have a life of their own. This website will attempt to explore this media/science clash chronologically, discussing the rise and fall of the ‘gay gene’ and the strong feelings that surround it.

Preliminary Findings:

The scientific findings began in 1991 when Simon LeVay, working at the Salk Institute for Biological Studies in San Diego, found subtle differences in the post-mortem brains of heterosexual and homosexual young men. (The majority of homosexual men also happened to have died from AIDS.) The cluster of neurons known as INAH 3 in the hypothalamus were reduced in size in homosexual men, much to the same degree that the same group of neurons is reduced in women. This region of the hypothalamus is also commonly thought of as participating in “the regulation of male-typical sexual behavior” (LeVay, 1991). LeVay, it should be noted, had strong personal reasons to pursue research in this area. A homosexual himself, he lost his partner of 21 years to AIDS. As was reported in a Newsweek cover-story in 1992, he felt that “. . . if I didn’t find anything, I would give up a scientific career altogether” (Gelman et al., 1992). It may also be said that he was not working without the sense of scope of his project: “It’s important to educate society. I think this issue does affect religious and legal attitudes.” Whether this personal interest affected his scientific practice is still left to be determined.

The most important paper that reported the ‘gay gene’ was from Hamer et al., a team of geneticists working for the National Cancer Institute (NCI). Dr. Dean Hamer and his colleagues reported in 1993 that, using DNA from homosexual siblings and their pedigrees, a gene for homosexuality seemed to be maternally linked and found on the Xq28 stretch of the X chromosome. He chose 40 pairs of homosexual brothers and found that 33 of them shared a set of five markers on the long arm of the X chromosome. In the July 19, 1993 edition of Science, Hamer reported that the linkage translated to a “99.5% certainty that there is a gene (or genes) in this area of the X chromosome that predisposes a male to become a heterosexual” (Hamer et al., 1993). Despite this statistical data, Hamer did try and put his findings in context and to qualify his statements using words such as “suggest” and “seem to indicate.” He reports that there are “probably several hundred genes in that region” and that most of them aren't identified. Despite his hesitiation, the media would soon project that his findings, of course, proposed that science was well on its way to finding the gene for homosexuality.

Hypothetical placement of the "gay gene," on the X chromosome. Picture courtesy NCBI.

A Media Response:

Prior to this article coming to print, the media reported only minor stories about scientists on the ‘hunt for a gay gene’. Although Newsweek had already had the topic of the search for a ‘gay gene’ on its cover, the article was merely speculation with only LeVay’s minor data to draw from. Immediately after the Hamer article was published, however, a media explosion ensued. USA Today was the first newspaper to report on the newly published data. Kim Painter begins the article with, “A predisposition for homosexuality appears to be written into the very genes of some men. And they get the key genes from their mothers,” and goes on to report that “‘The possibility of obtaining our findings by chance is extremely unlikely’ - below 1%, says lead author Dean Hamer” (Painter, 1993). Although this isn’t completely incorrect, the article never mentions the questions Hamer raised nor any of the problems they themselves raised about the study. Other newspapers followed suit and, it seems, the conclusions made on just this one experiment were regarded as scientific fact.

An article in Time magazine soon followed, reporting that the studies of family trees and DNA make the case for genetics as the cause of male homosexuality. Those associated with the study of the disease were directly quoted in the article, which was very insightful, especially in touching on the possible future of a world where sexual orientation is known from birth or pre-birth. Dr. Hamer says, “This is by far the strongest evidence to date that there is a genetic component to sexual orientation. We’ve identified a portion of the genome associated with it” (Henry, 1993). This is by far the most direct claim made by any scientist dealing with this subject. Dr. LeVay is also quoted as saying that “the DNA evidence [from Dr. Hamer] is much stronger than [previous] twin studies” (Henry, 1993). However, the tone of these articles would soon change.

Here also was the introduction of the two contrasting sides of the homosexual issue: the conservative groups denouncing homosexuality diametrically opposed with those groups that promote the rights of homosexuals. In the Time article, some anti-gay activists liken the ‘homosexuality gene’ to other genetic links that society finds undesirable, such as “mental and physical illness.” Also, Reed Irvine of the watchdog group Accuracy in Media says, “It’s a little more complicated than a hereditary factor. The media have given zero attention to the many, many homosexuals who have gone straight. I think it’s sending the gays the wrong message to say that you cannot change because it’s something your genes have determined” (Henry, 1993). The pro-gay organizations had mixed feelings: on the one hand, knowing that sexual orientation is pre-determined gives homosexuals some relief from blame – from society, their parents, or themselves – but at the same time there is something to be said about the concept of their sexuality being thought of as a genetic ‘disease.’ In this manner they could be ostracized even more.

Problems Arise and Confusion Remains:

The year 1995 marked beginning of the end of optimism for chromosome Xq28 as an indicator of male homosexuality. In this year Scientific American printed an article that mentioned the doubts in the scientific community over the genetics of homosexuality. LeVay’s findings, the article reports, “have yet to be fully replicated by another researcher” (Horgan, 1995). Also, one study contradicted Hamer’s results and Scientific American reported that he had “been charged with research improprieties and is now under investigation by the Federal Office of Research Integrity,” which was basically a result of his excluding “pairs of brothers whose genetic makeup contradicted his finding” (Horgan, 1995). This news report came in the November edition of the magazine, which was essentially presenting a retraction for the article the two scientists coauthored in 1994. Unfortunately for these two researchers, more bad news was to follow.

Science also reported that the study by Hamer was being questioned. A study by George Ebers and George Rice in 1995 indicated that “there is no reason to focus linkage studies on the X chromosome” and that there is “no evidence that gayness is passed from mother to son” (Marshall, 1995). Although these researchers agreed with the possibility that homosexuality is inherited, they found no clear evidence to justify Hamer’s claims.

Finally, in 1999, George Rice and George Ebers published their data. In the April edition of Science, the scientists show that their results, “do not support an X-linked gene underlying male homosexuality” (Rice et al., 1999 and Wickelgren, 1999). They found that the gay brothers looked at by the Hamer group were no more likely to share the Xq28 markers than would be expected by chance. This officially sounded the death-knell for the optimism held by Hamer et al. and others looking in this region for the gene leading to homosexuality.

When the 1993 Science article was written, a precursory “Research News” article was written by Robert Pool in the same magazine to report the findings of the Hamer group. In this article, Pool writes, “The field of behavioral genetics is littered with apparent discoveries that were later called into question or retracted” (Pool, 1993). A statement could not be more prophetic.

The Hamer group in 1993, during the initial success of finding the gay gene. Courtesy Science and Darrow Montgomery.

Dr. Hamer in 1995, after the Rice and Ebers data came to fruition. Courtesy Science and Darrow Montgomery.

Recently, no new news has been published about the “gay gene” that caused such a hubbub in 1992 and 1993. Jeffrey Satinover, M.D. provides an excellent website discussing the problems of hasty publishing and over-simplification in connection with the gay gene. Also, the Online Mendelian Inheritance in Man (OMIM) has a nice summary of the research on the gay gene. Other than this, the discussion of a gay gene, especially occuring in chromosome region Xq28, has ceased. This by no means implies that the discussion will not resume at some point in the near future, but no progress has been made recently. Unfortunately, even though the homosexual gene research was hyped by the media, the region of the X chromosome yields no functional proteins that relate to this study.

Conclusion:

Obviously, the genetics of homosexuality isn’t as simple as some in the media and elsewhere thought it would be. To be sure, little progress has been made after the initial findings provided such optimism. An interesting point can be made about the relationship between science and the media due to this study. The media, it seems, showered its skepticism on the interpretation of the scientific results while science, even with questionable practices among some of its own, corrected itself by placing the skepticism on the results themselves. Because the scientific process is necessarily reproducible, unsubstantiated claims fall by the wayside while those that can be corroborated stand the test of time.

References:

Gelman et al. Born or Bred? Newsweek 1992 Feb 24; 46.

Hamer et al. A linkage between DNA markers on the X chromosome and male sexual orientation. Science 1993 Jul 16; 261(5119):321-7.

Henry WA. Born Gay? Time 1993 Jul 26; 36.

Horgan, J. Gay genes, revisited. Scientific American 1995 Nov; 273(5):26.

LeVay S. A difference in hypothalamic structure between heterosexual and homosexual men. Science 1991 Aug 30; 253(5023):1034-7.

Marshall E. NIH's "gay gene" study questioned. Science 1995 Jun 30; 268(5219):1841.

Painter L. Is there a gay gene? USA Today 1993 Jul 16; 1A.

Pool R. Evidence for homosexuality gene. Science 1993 Jul 16; 261(5119):291-2.

Rice, et al. Male homosexuality: absence of linkage to microsatellite markers at Xq28. Science 1999 Apr 23; 284(5414):665-7.

Wickelgren I. Discovery of 'gay gene' questioned. Science 1999 Apr 23; 284(5414):571.

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