More thoughtful than most on this topic. BBC News.
Long discussion and a lot of handwaving about why there might be evolutionary advantage to presence of small level of same sex orientation disposition in a larger population.
At least this article adds...."
Dr William Byne, editor-in-chief of the journal LGBT Health, believes sexuality may well be inborn, but thinks it could be more complicated than some scientists believe. He notes that the heritability of homosexuality is similar to that for divorce, but "social science researchers have not… searched for 'divorce genes'. Instead they have focused on heritable personality and temperamental traits that might influence the likelihood of divorce."
For Qazi Rahman, it's the media that oversimplifies genetic theories of sexuality, with their reports of the discovery of "the gay gene". He believes that sexuality involves tens or perhaps hundreds of alleles that will probably take decades to uncover. And even if heterosexual sex is more advantageous in evolutionary terms than gay sex, it's not only gay people whose sexuality is determined by their genes, he says, but straight people too.
Well, at least we are getting some scientific research on homosexuality, and many questions remain.
"Since the early 1990s, researchers have shown that homosexuality is more common in brothers and relatives on the same maternal line, and a genetic factor is taken to be the cause. Also relevant - although in no way proof - is research identifying physical differences in the brains of adult straight and gay people, and a dizzying array of homosexual behaviour in animals."
~ Qazi RahmanKing's College London
"We know that women tend to like more feminine behavioural features and facial features in their men”
But since gay and lesbian people have fewer children than straight people, a problem arises.
"This is a paradox from an evolutionary perspective, how can a trait like male homosexuality, which has a genetic component, persist over evolutionary time if the individuals that carry the genes associated with that trait are not reproducing?"
~ Paul Vasey from the University of Lethbridge in Canada.