If you want to stir up trouble at a party--or better still, a bar--try bringing up the question of whether homosexuality is something people are born with or something they choose. The issue has always been controversial, and it's currently at the center of a national political debate as well, thanks to the question of gay marriage. As a result, whenever science has something to say about the biology of sexual preference, it's bound to make headlines.
That's exactly what happened last week. Researchers at the Karolinska Institute in Sweden who had earlier shown that hormonelike pheromones stimulate the human hypothalamus--a...