Study Shows Homosexuality Linked to Older Brothers

Researchers at Brock University in St. Catherine's, Canada, have found evidence that a male's sexual orientation is influenced by biological factors present before birth. A recent study showed that the more biological older brothers a man has, the more likely he is to grow up to be homosexual.

The study, conducted by Prof. Anthony Bogaert, provides strong evidence that sexual orientation may be the result of biological processes that happen in the womb. He studied nearly 1,000 men and found that the more older brothers a man has, the more likely he is to grow up to be homosexual. There was no affect if the older siblings were stepbrothers.

"If you have a biological brother, and you never even lived with that biological brother, this leads to a higher likelihood of male homosexuality," said Prof. Bogaert. "And so it suggests that there is probably some non-learning or non-environmental factor that is affecting sexual orientation."

"Given that there is perhaps a strong predisposition to be gay or not to be gay that is determined early on life, prenatally or even genetically, then this suggests that the idea that [homosexuality] is some kind of choice that people make and they are making bad choices and that kind of thing, I do not think that is really supported by the kind of research that we have been doing," Prof. Bogaert said.

The research on the influence of biological older brothers on male homosexuality is published in Proceedings of the National Academy of Sciences.