In a new study, researchers looked at 97 mothers of gay sons and 103 mothers without gay sons to see if there was any difference in how they handled their X chromosomes. The findings appear in the February 2006 issue of the journal Human Genetics. The research "confirms that there is a strong genetic basis for sexual orientation, and that for some gay men, genes on the X chromosome are involved," said study co-author Sven Bocklandt, a postdoctoral researcher at the University of California at Los Angeles.
"When we looked at women who have gay kids, in those with more than one gay son, we saw a quarter of them inactivate the same X in virtually every cell we checked," Bocklandt said. "That's extremely unusual." Forty-four of the women had more than one gay son. In contrast, 4 percent of mothers with no gay sons activated the chromosome and 13 percent of those with just one gay son did. The phenomenon of being more likely to inactivate one X chromosome -- known as "extreme skewing" -- is typically seen only in families that have major genetic irregularities, Bocklandt said.
What does this all mean? The researchers aren't sure, but Bocklandt thinks he and his colleagues are moving closer to understanding the origins of sexual orientation.
Dr. Ionel Sandovici, a genetics researcher at The Babraham Institute in Cambridge, England said, "We're trying to understand one of the most critical human traits: the ability to love and be attracted to others. Without sexual reproduction we would not exist, and sexual selection played an essential role in evolution," he said. "Yet, we have no idea how it works, and that's what we're trying to find out. "
This research suggests that genetics may play a part in sexual orientation. This is a vast difference than decades ago, where earlier versions of the DSM regarded homosexuality as a mental disorder. Genetic research rocks.
Resources:
Bocklandt, S. ; Horvath, S.; Vilain, E.; Hamer. D.H. ; Sandovici, I. (2006) Extreme skewing of X chromosome inactivation in mothers of homosexual men. Human Genetics, 118(6): 691-694.
The Gay Gene @ Frontline.
