[quote]Mishima wrote:
AlisaV wrote:
Well, it turns out that a gay man’s female relatives tend to be more fertile than average. It’s as though there’s a “man-loving” genetic trait carried on the X chromosome. It confers no Darwinian advantage if it winds up in a man, but in a woman it increases reproduction. I don’t think this is quite conclusive yet, but it’s intriguing and it makes sense.
stunning!
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A few more references, if you’re interested:
In 2004, Camperio-Ciani studied 98 homosexual and 100 heterosexual men and their relatives, which included more than 4,600 people overall. The female relatives on the mother’s side of the homosexual men tended to have more offspring than the female relatives on the father’s side. This suggests that women who pass on the gay trait to their male offspring are also more fertile. In comparison, the female relatives on both the mother’s and the father’s side of the heterosexual men did not appear to be as fertile, having fewer offspring.
In 2006, research published in the journal “Human Genetics” found that the genetics of mothers of multiple gay sons act differently than those of other women. Scientists 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. They found that almost one fourth of the mothers who had more than one gay son processed X chromosomes in their bodies in the same way. Normally, women randomly process the chromosomes in one of two ways – half go one way, half go the other. 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.”
In 2005, Dr. Brian Mustanski and his colleagues at the University of Illinois at Chicago, in the first-ever study combining the entire human genome for genetic determinants of sexual orientation, identified several stretches of DNA linked to sexual orientation on three different chromosomes. The bottom line, according to Mustanski, is that “genes play an important role” in determining whether or not men are gay or straight.
A recent study conducted by Canadian researcher and psychologist Anthony Bogaert reported that there was “no evidence that social interactions among family members played a role in determining whether a man was gay or straight.” What he found was that having one or more older brothers increases the likelihood that males will be gay - not based on social or environmental factors but based on biological events that occur in the womb.
http://www.nlm.nih.gov/medlineplus/news/fullstory_35335.html