Via the Guardian:
A study of gay men in the US has found fresh evidence that male sexual orientation is influenced by genes. Scientists tested the DNA of 400 gay men and found that genes on at least two chromosomes affected whether a man was gay or straight. A region of the X chromosome called Xq28 had some impact on men’s sexual behaviour – though scientists have no idea which of the many genes in the region are involved, nor how many lie elsewhere in the genome. Another stretch of DNA on chromosome 8 also played a role in male sexual orientation – though again the precise mechanism is unclear. Researchers have speculated in the past that genes linked to homosexuality in men may have survived evolution because they happened to make women who carried them more fertile. This may be the case for genes in the Xq28 region, as the X chromosome is passed down to men exclusively from their mothers.
Via the Telegraph:
Dr Bailey said: “Sexual orientation has nothing to do with choice. Our findings suggest there may be genes at play – we found evidence for two sets that affect whether a man is gay or straight. “But it is not completely determinative; there are certainly other environmental factors involved. “The study shows that there are genes involved in male sexual orientation. “Although this could one day lead to a pre-natal test for male sexual orientation, it would not be very accurate, as there are other factors that can influence the outcome.” Dr Alan Sanders, associate Professor of Psychiatry at Northwestern University, who led the study said that it was it was an ‘oversimplification’ to suggest there was a ‘gay gene.’ “We don’t think genetics is the whole story. It’s not. We have a gene that contributes to homosexuality but you could say it is linked to heterosexuality. It is the variation.”