Asked by: Anonymous
Studies with identical twins have shown some evidence for an inherited component to homosexuality. But that’s not quite the same thing as a ‘gay gene’. For example, a 1997 study at the University of Toronto showed that each older brother a man has increases his chance of being homosexual (see Focus, June 2009, p37). The inherited component of homosexuality seems to be much weaker in women than men but culture, lifestyle and early sexual experiences are probably more significant than genetics for both genders. Certainly, upbringing and culture have a big impact on the way that people acknowledge and define their own sexuality.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.