Joined: Oct. 2005
A genetic theory of homosexuality.
By William Saletan
Posted Wednesday, June 25, 2008, at 8:04 AM ET
Gay couples can't have biological kids together. So if homosexuality is genetic, why hasn't it died out?
A study published last week in PLoS One tackles the question. It starts with four curious patterns. First, male homosexuality occurs at a low but stable frequency in a wide range of societies. Second, the female relatives of gay men produce children at a higher rate than other women do. Third, among these female relatives, those related to the gay man's mother produce children at a higher rate than do those related to his father. Fourth, among the man's male relatives, homosexuality is more common in those related to his mother than in those related to his father.
Can genes account for these patterns? To find out, the authors posit several possible mechanisms and compute their effects over time. They conclude that only one theory fits the data. The theory is called "sexually antagonistic selection." It holds that a gene can be reproductively harmful to one sex as long as it's helpful to the other. The gene for male homosexuality persists because it promotes—and is passed down through—high rates of procreation among gay men's mothers, sisters, and aunts.
read the rest at Slate
Edited by stevestory on June 25 2008,13:59