Gay Genes?

Gay Pride Parade in BrazilA big federal study is underway to identify the specific DNA changes that contribute to being a homosexual. Note that scientists are not investigating whether or not being gay is genetic. The evidence is already pretty strong at this point that there is a genetic component to being gay. What they are looking for are the specific changes.

For example, one study showed that if one identical twin was gay, then the other was 50% of the time. If the two brothers were fraternal twins, then the odds dropped down to 22%. And if one brother was adopted, the odds were only 11%.

Another more comprehensive study gave similar results with both twins in an identical twin pair being gay around 32% of the time as compared to 13% of the time for fraternal twins. Lots of other studies have been done that show the same trend even if they don't have the exact same numbers.

These results strongly suggest genes are involved because identical twins share the exact same DNA. If both twins in an identical twin pair have some trait in common more often than do fraternal twins, then odds are that genetics plays a role.

These twin studies show that being gay is at least partly genetic. So the new study is really just looking to explain explain the older results.

That said, I am torn about whether I want this study to succeed or not. If it is successful, that'll shut up all those people who maintain that sexual preference is purely the result of personal choice. In my opinion, quieting those folks is a good thing. But finding the gay gene(s) may have unintended consequences. Some people may see being gay as akin to a genetic disease like cystic fibrosis or sickle cell anemia. As something to be minimized through carrier screening, embryo selection, or even abortion.

Scary, but I have heard people say things like this. Just the other day someone asked a friend of mine if homosexuality was genetic. They weren't merely being curious. They were hopeful that there was a gay gene so that homosexuality could be eliminated from the human population at some point. Yikes!

And that was here in the San Francisco Bay Area. Who knows what they are saying in Wyoming or Texas. Do we want to find the gene(s) responsible for homosexuality? Or are some things better left unknown? Comment below.

Dr. Barry Starr is a Geneticist-in-Residence at The Tech Museum of Innovation in San Jose, CA.

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