Back to Articles Index

Of course, everyone knows it’s true, right? It was reported on National Public Radio, in The Wall Street Journal and The New York Times, after all. “Research Points Toward a Gay Gene,” the Journal said. “Report Suggests Homosexuality Is Linked to Genes,” read the Times.

They were all reporting the release of a study in Science magazine in July 1993 that purported to find a genetic cause for homosexuality. Though the necessary caveats were added to the news stories, most people would already have turned off the radio or turned the page, thinking that homosexuality is caused by a gene.

But can you believe everything you read in the paper? Is there such a thing as a gay gene?

In the study the media was trumpeting, molecular geneticist Dean Hamer and his colleagues had performed a new kind of behavioral genetics study now becoming widespread—the so-called “linkage study.” Researchers identify a behavioral trait that runs in a family and is correlated to a chromosomal variant found in the genetic material of that family. Hamer’s study identified a link on the q28 region of the X chromosome in homosexual males.

Defining Terms

Even though a trait may have a chromosomal link, it does not necessarily mean it is genetic. Genetic traits are those, such as eye colors, that are coded for us by genes alone.

Each human gene can be thought of as a book that provides a complex set of instructions for the synthesis of a single protein. These proteins are then responsible for forming and operating everything else in the body.

Behavioral traits, such as weight, are influenced by genetics, but unlike genetic traits, most behavioral traits are programmed by multiple genes and things such as the environment in the womb, the mother’s health habits or postnatal effects of a virus. All of these and more may combine and influence one another throughout a lifetime. Behavioral traits, as opposed to simple, single-gene physiologic traits such as eye color, always interact in this way.

Demonstrating that any behavioral state is not only biological but genetic is well beyond our present research capacity. This is especially true for something so complex and nuanced as homosexuality. One psychiatric researcher, Brian Suarez, calculated that at least 8,000 people would be required for a study to confirm a behavioral trait as genetic. No study of homosexuality has come remotely close to these requirements.

Contested Evidence

As it is, the Hamer study is seriously flawed. Four months after its publication in Science, a critical commentary appeared in the same publication. It took issue with the many assumptions and questionable use of statistics that underlie Hamer’s conclusions, but not with his research methods and raw data, which met acceptable standards for linkage studies.

Genetics researchers from Yale, Columbia and Louisiana State Universities noted that much of the Hamer report focused on social and political ramifications of genetic homosexuality rather than discussing scientific evidence. They also indicated that the results were not consistent with any genetic model and should be interpreted cautiously.

Hamer responded, indicating that his research was not conclusive that Xq28 underlies sexuality, only that it contributes to it in some families, and that its influence was statistically detectable in the population that he studied.

Hamer gave another report in a 1994 issue of Science devoted to behavioral genetics. He indicated that complex behavioral traits are the product of multiple genetic and environmental agents. He clarified that “environment” meant not only social environment but also the flux of hormones during development, whether you were lying on your right or left side in the womb and a number of other factors.

Science revisited the topic this year, publishing two articles questioning supposed links to a gay gene. Both articles reference an independent genetic study conducted in Canada in 1989 with research continuing today by four researchers from the University of Western Ontario and Stanford Medical School. This study used 52 pairs of gay siblings from 48 families æHamer’s research used 40 homosexual brother pairs. The study concluded, “It is unclear why our results are so discrepant from Hamer’s original study. Because our study was larger than that of Hamer et al., we certainly had adequate power to detect a genetic effect as large as was reported in that study. Nonetheless, our data do not support the presence of a gene of large effect influencing sexual orientation at position Xq28.”

In other words, any claim to have found a “gay gene” were overblown if not outright wrong.

Figuring It All Out

What can we conclude about the biology of homosexuality? Consider a comprehensive review article, “Human Sexual Orientation: The Biological Theories Reappraised,” written by William Byne and Bruce Parsons from Columbia University in 1993.

The article reviews 135 research studies, prior reviews, academic summaries, books, and chapters of books—in essence the entire literature on homosexuality, of which only a small portion is actual research. The abstract summarized in its findings that there is no evidence at present to substantiate that biological factors are the primary basis for sexual orientation.

Whatever genetic contribution to homosexuality exists, it probably contributes not to homosexuality per se, but rather to some other trait that makes the homosexual “option” more readily available to some than others.

Most studies to date have many flaws. Some are caused by the intrusion of political agendas into what should be objective research, and some are due to the complex nature of the subject. These flaws must temper any conclusions we make. It is premature, and will almost certainly prove to be incorrect, to state that homosexuality is genetic.

Dr. Jeffrey Satinover is the author of Homosexuality and the Politics of Truth. He is a former Fellow in Psychiatry and Child Psychiatry at Yale University. He holds degrees from MIT, the University of Texas and Harvard. He serves as a medical adviser to Focus on the Family.

Back to Articles Index