Biologists propose a new explanation for same-sex attraction

by Mike Andrew - SGN Staff Writer

Researchers from the National Institute for Mathematical and Biological Synthesis have developed a new theory to explain why some people are Gay.

In an article published December 11 in U.S. News and World Report, the scientists put a new twist on previous thinking that Gayness is hereditary. The trait is 'epigenetic,' they said - carried not by genes, but by markers that encode additional layers of information.

While Gayness has long been thought to be in some way hereditary, scientific consensus was that it could not be strictly genetic, because there are many pairs of identical twins with differing sexual orientations. In addition, if Gayness were strictly genetic, it could be expected to die out over many generations because Gays and Lesbians would be less likely to reproduce.

STIGMA STIFLES RESEARCH
William Rice, an evolutionary biologist at the University of California at Santa Barbara and lead author of the new study, said that biological studies of Gayness have been held back by social attitudes.

'Most mainstream biologists have shied away from studying it because of the social stigma,' Rice said. 'It's been swept under the rug - people are still stuck on this idea that it's unnatural. Well, there are many examples of homosexuality in nature - it's very common.'

Same-sex sexual behavior has been observed in black swans, penguins, sheep, and other animals, he added.

Gayness is carried by 'epi-marks' that control how certain genes are expressed, Rice believes. Usually the epi-marks are 'erased' between generations, Rice said, but in the case of Gay and Lesbian individuals, they are not.

'There is compelling evidence that epi-marks contribute to both the similarity and dissimilarity of family members and can therefore feasibly contribute to the observed familial inheritance of homosexuality and its low concordance between [identical] twins,' Rice said.

Rice and his team created a mathematical model that explains how Gayness is passed through epi-marks and not genes. The markers give mothers and fathers an evolutionary advantage by protecting them from producing too much or too little testosterone, but if they are not 'erased' between generations - as they normally are - their offspring may be Gay.

'These epi-marks protect fathers and mothers from excess or underexposure to testosterone - when they carry over to opposite-sex offspring, it can cause the masculinization of females or the feminization of males,' Rice says.

His theory is that in Gay men the genetic epi-marks would result in less testosterone than in straight men, and conversely more testosterone in Lesbians than in straight women.

'EASY TO TEST'
Rice notes that these markers are 'highly variable' and that only the strongest epi-marks will result in Gay offspring.

'We've found a story that looks really good' for explaining Gayness, Rice said.

'There's more verification needed, but we point out how we can easily do epigenetic profiles genome-wide. We predict where the epi-marks occur - we just need other studies to look at it empirically. This can be tested and proven within six months. It's easy to test. If it's a bad idea, we can throw it away in short order.'

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