Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: thedoc on 20/05/2013 02:30:01
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Brian asked the Naked Scientists:
There seems to be increasing evidence from various researchers that homosexuality is determined in the womb rather being a personal choice.
Could you tell your followers what evidence there actually is and how convincing it is.
What do you think?
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Not directly relevant to the actual evidence itself, but relevant to our changing perceptions of that evidence over time: http://scientopia.org/blogs/neuropolarbear/2013/05/16/why-are-some-people-homosexual/
I would be surprised if this was not yet another complicated tangle of genes & environment, rather than one simple mechanism....
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As you say, the article you refer us to talks more about the social construct; but regarding whether there is some sort of physiological mechanism, I have heard that there is some evidence that men are more prone to being gay if they follow a long line of older sisters. But is there actually any evidence for this, or is it just apocryphal?
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... I have heard that there is some evidence that men are more prone to being gay if they follow a long line of older sisters. But is there actually any evidence for this, or is it just apocryphal?
I heard it was older brothers ...
The fraternal birth order effect is the strongest known biodemographic predictor of sexual orientation. According to several studies, each older brother increases a man's odds of having a homosexual orientation by 28–48%. The fraternal birth order effect accounts for approximately one seventh of the prevalence of homosexuality in men. There seems to be no effect on sexual orientation in women, and no effect related to the number of older sisters...
The effect has been found even in males not raised with their biological brothers, suggesting an in-utero environmental causation. To explain this finding, a maternal immune response has been hypothesized.
http://en.wikipedia.org/wiki/Fraternal_birth_order_and_male_sexual_orientation
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Ah, thanks; though I am sceptical about an "immune response" - sounds dubious to me...