An American study has found new evidence that male homosexuality is influenced by genes – but environmental and social factors also play a role.
In the study, which was presented at a Science of Sex and Attraction event in Chicago, scientists tested the DNA of more 400 sets of gay brothers and their heterosexual relatives, to find out if some men are predisposed to being gay.
Genetic factors account for between 30 per cent and 40 per cent of what decides whether a man is gay or straight, according to the research.
Scientists found that a region of the X chromosome Xq28 had an impact on male sexuality, as did a stretch of DNA on chromosome 8.
Dr Michael Bailey, of Northwestern University, Illinois, who col-led the study 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 work has not yet been published, but it builds on a previous study carried out in 1993 by Dr Dean Hamer from the US National Cancer Institute, who also found that gay men shared genetic signatures on the X chromosome.
However, the findings of the study raise the prospect of a genetic test that could be used to determine a bay’s sexual orientation in the womb.
http://www.independent.co.uk/news/world ... 27683.html