Zeroing in on the “Gay Gene”

The largest study yet of the genetic roots of homosexuality links sexual preference in men to two regions of the genome.

By | November 19, 2014

© ALEKSANDAR STOJKOVIC/SHUTTERSTOCKAt least in men, homosexuality may be a function of genetics, according to a study of more than 400 pairs of gay brothers. The research, published yesterday (November 18) in Psychological Medicine, confirms the role of a stretch of the X chromosome in determining sexual preference in men, a finding first suggested more than 20 years ago. Geneticist Dean Hamer, scientist emeritus at the National Institutes of Health, published a study in 1993 that proposed that Xq28, a region of the X chromosome, might play a role in determining whether a man was gay. “When you first find something out of the entire genome, you’re always wondering if it was just by chance,” Hamer told Science of the new study, adding that the research “clarifies the matter absolutely.”

Hamer, who recently wrote an opinion piece in The Scientist about the responsibilities of researchers who study sexual orientation, only studied 38 pairs of brothers in his 1993 study, but he told New Scientist that he sees the new paper as confirmation of his work. “Twenty years is a long time to wait for validation, but now it’s clear the original results were right,” he said. “It’s very nice to see it confirmed.”

But as was the case in 1993, not all researchers are convinced that science is homing in on the biological roots of sexual preference. Even the senior author on the Psychological Medicine paper, Northwestern University psychologist Michael Bailey, had his doubts. “I thought that [Hamer] did a fine but small study,” he told Science. “If I had to bet, I would have bet against our being able to replicate it.”

But when Bailey, who also wrote an opinion piece for The Scientist on the search for the biological roots of homosexuality, and his colleagues analyzed single nucleotide polymorphisms (SNPs) in the DNA of the brother pairs, they found five SNPs that were commonly shared by all the gay men. And those SNPs clustered in the Xq28 region on the X chromosome and in the 8q12 region of chromosome 8.

Bailey and his colleagues are now working on a genome-wide association study to confirm the results of their genetic linkage research. This analysis, which will include DNA samples from more than 1,000 additional gay men, may narrow the search for genetic signals for homosexuality down to individual genes. “It looks promising for there being genes in both of these regions,” Bailey told Science. “But until somebody finds a gene, we don’t know.”

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Avatar of: mlerman

mlerman

Posts: 53

November 19, 2014

Dr. Dean Hamer for many years used the budget provided by the NCI on cancer research to work on the homosezuality problem. Michael Lerman, M.D., Ph.D. 

Avatar of: W. Boernke

W. Boernke

Posts: 18

November 19, 2014

All genes are subject to natural selection.  Natural selection is best defined as differential rates of reproduction.  What is a homosexual's rate of reproduction?  Any gene that predisposes a person to refrain from mating with the opposite sex would be no different than a lethal gene that causes death before puberty.  The gene for Huntington's disease is a lethal, but gene expression occurs after reproduction, so it is passed on. Woody Guthrie died of Huntington's disease, yet he produced children.

If there is a genetic basis for homosexual behavior, how do you explain the ancient Greeks?  Alexander the Great had male lovers when he was conquering the world (Greek soldiers were encouraged to have male lovers because one is highly motivated to fight when fighting alongside a lover).  At some point Alexander realized he needed a male heir, so he married Roxanne. If you could ask Alexander if he was bisexual, he would have thought you are nuts.  When I am in battle, I have male lovers.  When I need to reproduce, I get married.

Avatar of: Nemo

Nemo

Posts: 4

November 19, 2014

I suggest the positive expression of the Xq28 gene be called Fabulous or FAB+.

Avatar of: Jenny Graves

Jenny Graves

Posts: 1

November 19, 2014

It makes more sense if you consider "gay genes" as "male loving genes." In female relatives of gay men they are an evolutionary advantage. See my article in TC <https://theconversation.com/born-this-way-an-evolutionary-view-of-gay-genes-26051>

Avatar of: jimdavis11

jimdavis11

Posts: 1

May 2, 2015

I have seen reports 5 genetic combinations are common. One to five can be included. It makes sense because all of my gay freinds ask me this question. Could you change your prefernce. I can't and I don't think they can either. Nor do I want them to. Not one has ever hinted that I do so.

Two questions I like to ask is, 1. Is god perfect? 2. Is the bible perfect? Then I tell them about the 5 genetic combos!

Whew!

 

Avatar of: orbachd

orbachd

Posts: 2

May 16, 2015

To w. Boernke, you asked how genes can be passed to the next generation is gay males are not reproducing. Other studies show this gene to be linked to a higher fecundity in women. That is that they seem to produce far more offspring. While some gay males don't reproduce (and some do) their siblings are 50 percent genetically identical to them and further, if they happen to have a female sibling, the same x chromosome could still be passed along. Higher fecundity, means evolutionarily advantageous, and siblings that are 50 genetically identical.
Avatar of: orbachd

orbachd

Posts: 2

May 16, 2015

To w. Boernke, you asked how genes can be passed to the next generation if gay males are not reproducing. Other studies show this gene to be linked to a higher fecundity in women. That is that they seem to produce far more offspring. While some gay males don't reproduce (and some do) their siblings are 50 percent genetically identical to them and further, if they happen to have a female sibling, the same x chromosome could still be passed along. Higher fecundity, means evolutionarily advantageous, and siblings that are 50 percent genetically identical.

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