Re: What is this nonsense about the gay gene?

Clara N. Fitzgerald (cfitzger@s.psych.uiuc.edu)
13 Nov 1995 22:58:01 GMT

ang42@sfsu.edu (Angelique Skiman) writes:
> Can anyone tell me about the study recently conducted that has
>supposedly found a gay gene on the X chromosome? This seems very unlikely
>to me. There is such a wide variety of sexual behavior that I doubt a
>single gene makes a person gay. If such a gene exists, wouldn't it make
>sense that women would not be gay? If they have two X chromosomes, wouldn't
>the "normal" X mask the effects of the gay gene? However, there obviously
>are a lot of gay women out there.

My understanding of the study was that a fragment of the X chromosome
was somewhat more likely to be found in gay men than in others - this
particular gene did not seem to be associated with gayness in women.
The phrase "this gene [fragment] _causes_ a certain trait" is usually
meant to be interpreted "there is a statistical link between this
gene and the trait; there are [almost undoubtedly] other genes involved,
whose interaction we have not yet studied".
Therefore,
The fragment is inherited from the mother.
Its presence alone is unlikely to cause the trait (other genes are involved,
and the correlation is not perfect).
This fragment does not occur in all [possibly most] gay men; it's just
the first genetic marker that has shown a correlation.
If this marker also applies to women, there should be a sex-linked
pattern [which I can't remember right now, but something like i/2
men and i^2 women expressing a recessive trait (i<<1) ].
Part of the interest in this finding was the speculation of evolutionary
advantage to a female of having a homosexual male relative. I'm not
quite sure how this would be formulated.

--
-Clara A. N. Fitzgerald cfitzger@s.psych.uiuc.edu
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