Progress on finding a gay gene

A new study has just been published that has some evidence that may support the gay “gene” (or “genes”) concept.

Some research has focused on a number of different areas of human biology. Such diverse areas as brain anatomy, brain physiology, male children’s birth order, mother’s genetic makeup, psychology, social interactions and others, may play a role.

For example, some researchers have found differences in certain physical structures in the brains of straight and gay men. Structures that seem to be different may be the anterior commissure, massa intermedia, suprachiasmatic nucleus and other areas of the hypothalamus.

Other research has shown that birth order of male children in the same family seems to be linked to an increasing chance of later-born children being gay.

Xq28

In the early 1990s some research on the genetics of gay male brothers showed that gay men had more gay uncles and cousins on the maternal side of their families than they did on the paternal side. This implied that there might be a gene on the X chromosome (inherited only from the mother) that was causing some of these men to be gay. Further testing showed that there was an area of X chromosome (Xq28) that was found in a much higher percentage in gay brothers than would be expected. Over the next 20 years, some studies confirmed this result, but a few got significantly different results. And at least one small study showed the opposite result. There’s been some controversy as to whether there is a gay gene, and if so, is it on the X chromosome in the area of Xq28.

Chromosomes 7, 8 and 10

Human chromosomes, by Steffen Dietzel.

Human chromosomes, by Steffen Dietzel.

As research continued, other areas of different chromosomes were implicated as being involved in determining whether an individual male child developed a gay or straight sexual orientation. Some areas of chromosomes 7, 8 and 10 may also contribute to the cause of being gay. Interestingly, some animal studies have shown that a related area of the X chromosome in those animals predisposes to gayness as well.

The most recent study: Xq28 and Chromose 8

The most recent study used a large number of gay brothers and looked closely at their genetic makeup. The findings showed that a discrete area of the X chromosome (Xq28), and a portion of chromosome 8, seemed to predispose to their gayness.

The authors of the study concluded:

Results, especially in the context of past studies, support the existence of genes on pericentromeric chromosome 8 and chromosome Xq28 influencing development of male sexual orientation.

But the statistical analysis doesn’t conclusively demonstrate that the correlation is true. Therefore it doesn’t prove that this particular genetic combination is the cause of homosexuality. But it may suggest that they play a role in determining sexual identity. Perhaps the interactions of the products of these genes predisposes to one’s becoming gay.

While it would be convenient to think that the cause of someone’s sexual orientation might be entirely genetic, research indicates that other factors (biologic, social, psychological, etc.) may still play a role.


Mark Thoma, MD, is a physician who did his residency in internal medicine. Mark has a long history of social activism, and was an early technogeek, and science junkie, after evolving through his nerd phase. Favorite quote: “The most exciting phrase to hear in science... is not 'Eureka!' (I found it!) but 'That's funny.'” - Isaac Asimov

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  • ronbo

    Part of this was settled science in the early ’80’s. The part of the brain that stimulates sexual excitment begins with scent. During gestation, hormonal changes in the MOTHER cause trigger development of different parts of the brain – one of which is sensitive to scent/pheromones (both male and female). When stress or sensitivity causes the MOTHER to produce hormones out or sequence or proportion, the developing brain creates sensitivity to either female or male pheromones.

    Sexuality is plastic, so this is is not the only cause. However, it explains both homo and hetro sexuality. The most common sequence creates hetro, but human sexuality is PROGRAMMED to produce homosexuality. Since stress is a major factor triggering homosexuality, it is logical to conclude that nature produces homosexuals as remedy for stress as the metaphorical steamvalve.

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  • Denver Catboy

    Sometimes you have to play the long-game. Cosby has fallen enough out of the public view that his popularity is flagging, and he doesn’t have the resources he had when he was younger. Could she be making **** up? Of course, always. But when you get more than one ‘she’, the chance of **** making up decreases. Eventually it crosses a threshold and achieves critical mass.

    Sadly, Crosby is far outside the statute of limitations for any sort of charges from what he did 30 years ago, but if he did something within the last few years, THAT is actionable. We’ll see how it turns out.

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  • docsterx

    Most of the studies mentioned above, including the most recent one were done on males. So drawing conclusions about if those genes affect the female sexual orientation would be speculation. In these research papers the authors refer to “homosexuality” and don’t use the word “gay” probably because that is not thought of as a scientific term.

    When the press publishes information on these studies, they tend to use terms like “gay gene” because that phrase was coined years ago as genetic research started to point to an inborn cause for males being gay. Also, it increases hits on the site. “Gay marriage” gets more hits than “LGBT marriage” which often gets more hits than “Marriage Equality.”

    I’m not sure how calling something that may cause homosexuality a “gay gene” is stigmatizing.

  • MidCoast

    Way back in the old days, bigots used to rant and rave that being gay was unnatural. Then it was found homosexuality occurred throughout the animal kingdom, so they switched to “we are better than animals!”* They are like terrorists: they just keep changing their methods.

    *Homophobes are not in any sense better than any animal I have ever known.

  • Tysalpha

    Have researchers discussed the effects of these various genes on female children? Because it’s very stigmatizing to say they are “gay” genes… when in fact they could just be “orientation toward men” genes, that are expressed in women in XYZ ways. We benefit not only by showing that their IS a gene (or genes) but also by showing how everything is interrelated.

  • Butch1

    Crosby was and is a bully and he used it to his advantage. No one would have believed her.

  • Butch1

    That is another dilemma they may have to face; I wonder if they will have an exception to their rule as they do with abortion and capital punishment? Somehow, they are about to differentiate the difference between killing in these two subjects without any problems.

  • Butch1

    Of course, there will always be those who dismiss everything no matter what conclusive evidence we have to offer them. “The bible says . . .” fill in the space.

  • Butch1

    Just a little more evidence leaning our way.

  • docsterx

    ROTFLMAO, an unexpected bonus(?)!

  • MyrddinWilt

    Its not a gene, its environmental: Lead poisoning.

  • 2karmanot

    It would certainly give Regressives an opportunity to embrace abortion.

  • UncleBucky
  • UncleBucky

    First find the gene for greed, hate and Libertarianism….

  • docsterx

    It’s not genetic, it’s a choice!

  • docsterx

    I’ve read some comments on other sites from people who are really excited about the prospect of finding a gay gene(s). They seem to think that if “gayness” can be nailed down to a specific chromosomal site that it will legitimize being gay. That is, then “gay” could no longer be considered a choice. It would be determined because of the science involved. That may convince a lot of people who believe in science. But I doubt that it would make any difference to the millions out there who deny science or substitute religion for science. For example, I doubt that if ever a gay gene is discovered, that that would change the minds of either Bachmann, Santorum, Gallagher, Robertson or the others who cling to those same beliefs.

  • GarySFBCN

    Slippery slope here we come.

  • Bill_Perdue

    My father was bisexual or closeted. He had a long relationship with a monk at the parish in our neighborhood and when I showed up at the parochial school brother ‘John’ adopted me and ran the bullies ragged if they messed with me, or any gay kid.

    My fathers sexuality is one of the reasons I’ve always embraced the theory that a large part of being gay is genetic. The other is the overwhelming power of our genetic heritage that can break through all the crap thrown at us. The idea that being gay is learned behavior is wrong headed but in cultures where being gay is accepted it makes it easier for our genetic heritage to express itself.

  • nicho

    Not to mention that 32 years ago, Cosby was at the top of his popularity. And given the climate at that time, had the woman made the charges, she would have been smeared and discredited by the Cosby machine.

  • MyrddinWilt

    People made similar comments about Jimmy Saville’s accusers in the UK until the shear number overwhelmed. In the case of Cosby they didn’t all wait 35 years. But the ones who reported immediately were not believed.

  • caphillprof

    Probably the same gene that causes a woman to wait 32 years before yelling rape.

  • Indigo

    More importantly, which gene causes heterosexuality?

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