Opinion > Columnists > Brent Castillo

Posted on Thu, Nov. 20, 2008

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Homosexuality is not wholly genetic

I don't usually write follow-up columns, but this time I feel compelled to because of the large and spirited response to last week's column on whether gay marriage is a civil right.

The term "bigot" was used fast and freely to describe me and people like me who don't believe homosexual marriage is on par with heterosexual marriage. But setting aside the name-calling, I'd like to address one issue raised by several readers who e-mailed me. They argued that homosexuality is wholly genetic and therefore should be put in the same category as race.

The problem is that the science behind homosexual behavior is -- at best -- inconclusive and doesn't elevate it to minority status. That status requires that it be an innate, immutable characteristic, such as race or a disability. For example, I'm Hispanic and will always be Hispanic.

Homosexuality doesn't meet that standard.

One influential study done by J. Michael Bailey and Richard Pillard in 1991 tried to show the genetic roots of homosexuality by researching sets of twins in which at least one was homosexual. They said they found elevated occurrences of the siblings also being homosexual, but their findings were called into question because of their methodology. A primary concern was that those who participated in the research had an interest in reinforcing the study's hypothesis.

In 2000, the scientific team of Bailey, Dunne and Martin overcame the methodological weakness by using a larger sample of people. Their results and a couple of similar studies were reviewed by the Annual Review of Sex Research in 2002, which reported that both genetics and environmental influences affect sexual orientation.

In 1993, research by geneticist Dean Hamer was touted as having found a "gay gene." Hamer didn't make such an outright claim, but many media outlets lead us to believe that is what he had discovered. In 1994, Hamer said in the book "The Science of Desire" that "we knew also that genes were only part of the answer. We assumed the environment also played a role in sexual orientation, as it does in most if not all behaviors."

Another set of researchers failed to replicate Hamer's gay gene research. "It is unclear why our results are so discrepant from Hamer's original study," the research team of Rice, Risch and Ebers said in 1999. "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."

Research continues to prove the overarching influence of environmental factors. A report this year in the Journal of Women's Health showed that childhood sexual abuse can sometimes play a role in sexual orientation.

Science has shown that there is a genetic element to homosexuality, but it's more like that of an obesity gene than one of race. The findings also have reinforced the critical role that environment plays in people's sexuality. That's an important distinction that separates it from skin color.

Giving any type of behavior the same status as immutable minority characteristics is not based on good science. There's nothing bigoted about saying so.

Brent Castillo appears in Opinion on Thursdays. Reach him at bcopinion@gmail.com.