Scientists at Northwestern University claim to have found two sets of genes that may contribute to male homosexual orientation, but estimate that it only contributes about 40% to the chance of someone developing a homosexual orientation. The other 60% is determined by environment, which includes social factors. This is consistent with what researchers have said all along. Sexual orientation cannot be determined entirely by biology. Nature plus nurture together most likely contribute to same-sex attraction.
Sarah Knapton, “Being homosexual is only partly due to gay gene, research finds”; available from http://www.telegraph.co.uk/science/science-news/10637532/Being-homosexual-is-only-partly-due-to-gay-gene-research-finds.html; Internet; accessed 25 March 2014.