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US scientists find being gay is 40% genetic

A study of 400 pairs of twins has found that gay men share genetic signatures in their chromosomes but also that sexual orientation is not entirely genetic in cause
Human chromosomes
Photo by Steffen Dietzel

New research by Chicago’s Northwestern University indicates that specific genes can increase the chance that a man will be homosexual.

Researchers studied the genetic makeup of 400 pairs of twins and found that those that were openly gay were more likely to share similarities in the Xq28 region of their X chromosome and also in Chromosome 8.

The researchers believe this shows that genetics is about 30 to 40% responsible for determining a man’s sexuality.

The rest, they believe, is determined by environmental factors such as a mother’s hormonal levels during pregnancy.

‘Sexual orientation has nothing to do with choice,’ researcher Professor Michael Bailey told The Times.


‘It is not completely determinative, there are certainly other environmental factors involved.’

However Hamer said that if someone tried to use these genes as a pre-natal test for homosexuality it would not be very accurate as the bigger picture was yet to be understood.

The region of the X chromosome that Professor Bailey found to be shared by gay men is the same that American geneticist Dean Hamer suggested was linked to homosexuality in 1993 – leading to it being dubbed ‘the Gay Gene.’

Corresponding genes for lesbians are yet to be identified.

Previous research has shown that gay and straight men’s brains are structurally different and that gay men’s brains respond to the sex pheromones produced by other men whereas heterosexual men’s brains respond to the sex pheromones produced by women.

The results come as Ugandan President has asked a team of scientists to investigate whether homosexuality is a choice before he will sign that country’s Anti-Homosexuality Bill.

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@ Matt Jones: Actually, "Xenophobia - the fear and hatred of strangers or foreigners or of anything that is strange or foreign" had tremendous survival advantages for our earliest ancestors, and as such predates organized religion by more than 1,000,000 years of evolutionary history, (assuming you believe in evolution.) Most world religions promote higher mental functioning in regard to "doing unto others as you would have them do unto you," as opposed to the more base and superstitious actions like we Westerners hold against the primitives of Russia. Which you would have known had you done a little bit of research.

@ Bob Pattinson: As a practicing atheist, you may want to look in a mirror and consider your need of an imaginary "enemy" to hate in order to convince yourself that you are superior to the rest of Humanity. You never seem to shy away from expertly painting wide swaths of humanity in the very same way you complain of others painting you.

@ Benji Diamond: Here in Santa Clara County, California, it seems like most of the Gym-O-Sexuals hang out at 24 Hour Fitness - or so I am told.