Aug. 30, 2019
An all-star team of scientists has just published a new “genome-wide association study” (“GWAS”) in the journal Science, on a massive sample of nearly half a million individuals, that attempted to identify if genetic factors contribute to same-sex sexual behavior.
The key take-away? “[T]here is certainly no single genetic determinant [of same-sex sexual behavior] (sometimes referred to as the ‘gay gene’ in the media).” Eric Vilain, a genetic medicine researcher, agrees, telling the Washington Post that the study marks the end of “the simplistic concept of the ‘gay gene.’”
The study does suggest that all genetic factors put together may account for, at most, a third of the variation in same-sex sexual behavior in the population. What does that imply? That at least two thirds of the variation is accounted for by social, cultural, and environmental factors—not genetics. So much for the idea that people are “born gay.”
The media is conceding that there is not one “gay gene,” while still pushing the idea of genes being involved in homosexuality as far as they can. The New York Times begins its headline, “Many Genes Influence Same-Sex Sexuality,” while the Washington Post headline emphasizes that “genetics are linked to same-sex behavior.”
While these statements are true, where the media fails the public is in not adequately distinguishing the idea of genetic “influence” or a “link” from the popular idea of the “gay gene” (or “genes”)—the belief that there is some genetic factor that determines, inexorably and immutably, that some individuals are destined to become homosexual.
There is a huge difference between genetic “influence” and genetic “determination.” Science has shown that many personality traits and behaviors are “influenced” by genetics, but no one would ever say those characteristics are inborn and immutable.
For example, here is how the study actually reports that “one third of the variation” figure I mentioned above:
[W]e estimated broad-sense heritability—the percentage of variation in a trait attributable to genetic variation—at 32.4%.
Put in decimal form, that is a “heritability” of about .32. But here are the “heritability” rates that scientists have identified for some other psychological traits:
- Conservatism .45-.65
- Right-wing authoritarianism .50-.64
- Religiousness .30-.45
Yet virtually no one would ever say that these traits are inborn and immutable—even though their “heritability” is as high or higher than for same-sex sexual behavior.
Yet even the study’s 32% “heritability” rating may exaggerate the link between any specific genes and homosexual behavior. The study identified only five locations on the genome with a statistically significant link to same-sex sexual behavior. (None of those were on the X-chromosome—where the original “gay gene” was supposedly located in a 1993 study.) Only three of those associations could be replicated in an analysis of other (smaller) databases. The study reported that “all tested genetic variants accounted for 8 to 25% of variation in same-sex sexual behavior”—a broad range, and lower than the 32% “heritability” estimate. The genetic differences were so small that they “could not be used to accurately predict sexual behavior in an individual.”
One methodological problem with the study is that the primary measure of “nonheterosexuality” is whether the respondent answered yes or no to the question of whether they have ever had sex with a person of the same sex. A large percentage of that population does not self-identify as “gay” or “lesbian,” and may not engage exclusively or even primarily in same-sex sexual relationships, so it is not at all clear whether this is the best way of approaching the question. The study did find there was a genetic correlation with the proportion of same-sex sexual partners—but it did not involve the same genetic variants as the “binary” variable!
The New York Times report suggests—at length—that some pro-LGBT spokesman and scientists were concerned about even conducting the research. This seems a backhanded way of admitting that the findings do not serve the political purposes of the LGBT political movement.
For example, the study showed that same-sex sexuality correlated not only with certain genes, but with certain personality traits (“loneliness,” “openness to experience”), risky behaviors (smoking, cannabis use), and mental disorders (depression and schizophrenia). The study cautioned:
We emphasize that the causal processes underlying these genetic correlations are unclear and could be generated by environmental factors relating to prejudice against individuals engaging in same-sex sexual behavior, among other possibilities . . .
But if the “causal processes underlying . . . genetic correlations” with mental illness and substance abuse “could be generated by environmental factors,” then the same must be said about the correlations with same-sex sexual behavior itself.
That movement has depended for decades on the myth that people are “born gay” and cannot change, probably because of some undiscovered “gay gene” that immutably determines their sexuality. Demands for LGBT “civil rights” have rested largely on assertions that sexual orientation, like race, is a characteristic that is inborn, genetic, and immutable.
Although evidence for those claims has always been lacking, this study debunks them more decisively than any previous one. It is ironic that those on the Left routinely accuse conservatives of being “anti-science”—yet in this case, it is they who fear the results of a serious scientific inquiry.
For our part, Family Research Council is happy to embrace the study’s conclusion about the “complexity” of same-sex sexuality, and “the importance of resisting simplistic conclusions.” The authors are correct in saying that “there is a long history of misusing genetic results for social purposes”—but on this issue, it is the LGBT activists who have long promoted the myth of the “gay gene” who are most guilty.