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from Clinical/Therapeutic Issues
New Study Alleges That Mother's Genetics
May Account For Gay Sons
February 22, 2006 -
A study published in Human Genetics alleges that researchers have found that a
mother's genetic make-up may produce gay sons.
The study was co-authored by postdoctoral researcher Sven Bocklandt at the
University of California, LA. According to Bocklandt, his study "confirms that
there is a strong genetic basis for sexual orientation, and that for some gay
men, genes on the X chromosome are involved."
Bocklandt and his associates studied "X-chromosome inactivation" and surveyed 97
mothers with gay sons and 103 mothers without gay sons to see how they handled
their X-chromosomes. "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," said Bocklandt. He also said: "What's really
remarkable and very novel about this is that you see something in the bodies of
women that is linked to a behavioral trait in their sons. That's new, that's
unheard of."
Psychologist Dr. Warren Throckmorton has reviewed Bocklandt's study and
commented on it on his blog on February 21:
This kind of stuff is interesting, of course, but the conclusions drawn by the
researchers is speculative: "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." The findings I read
in the abstract do not "confirm" anything. Furthermore, the study as described
could not provide any pathway from a putative genetic mechanism to behavior. All
they have shown is there are group differences.
As I look at it, none of this is very enlightening unless the temperament and
environment of the sons is also taken into consideration. There are potential
intervening variables that are not even considered by these researchers (e.g.,
gender atypical temperaments). GAT may be related to these changes in the X
chromosome but I doubt this was taken into account.
ABSTRACT
Human Genetics
Issue: Volume 118, Number 6
Date: February 2006
Pages: 691 - 694
Extreme skewing of X chromosome inactivation in mothers of homosexual men
Sven Bocklandt, Steve Horvath, Eric Vilain and Dean H. Hamer
Abstract Human sexual preference is a sexually dimorphic trait with a
substantial genetic component. Linkage of male sexual orientation to markers on
the X chromosome has been reported in some families. Here, we measured X
chromosome inactivation ratios in 97 mothers of homosexual men and 103
age-matched control women without gay sons. The number of women with extreme
skewing of X-inactivation was significantly higher in mothers of gay men
(13/97=13%) compared to controls (4/103=4%) and increased in mothers with two or
more gay sons (10/44=23%). Our findings support a role for the X chromosome in
regulating sexual orientation in a subgroup of gay men.
Updated: 28 February 2008
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