Gender bending
Genes that make some people gay make their brothers and sisters fecund
THE evidence suggests that homosexual behaviour is partly genetic. Studies of identical twins, for example, show that if one of a pair (regardless of sex) is homosexual, the other has a 50% chance of being so, too. That observation, though, raises a worrying evolutionary question: how could a trait so at odds with reproductive success survive the ruthless imperatives of natural selection?
Various answers have been suggested. However, they all boil down to the idea that the relatives of those who are gay gain some advantage that allows genes predisposing people to homosexual behaviour to be passed on collaterally.
This article appeared in the Science & technology section of the print edition under the headline "Gender bending"
Science & technology October 25th 2008
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