Posted by: Chris | November 27, 2009

Epigenetics and the Gays

National Geographic promulgates a similar theory to the one discussed here earlier.  Similar to the Klar hypothesis, it relies on epigenetic effects during development to regulate hormone expression (and from there brain development).  It is more simplistic than the Klar hypothesis, arguing that lowered testosterone production causes the an inadequate masculinity of the gay brain, with no accounting for the other features correllated with male homosexuality, namely left-handedness and counter-clockwise hair whorls*, that would be unaffected by fetal testosterone levels.  In that respect I still prefer the Klar hypothesis, but there is some more circumstantial evidence to the insufficient masculinization hypothesis.  For example, gay males tend to be more similar straight females in terms of spacial reasoning and other tasks.

Also, both hypotheses are compatible with the Feynay effect, as the hormonal or immuno-response alterations caused by previous male residents in the mother’s womb would in both cases serve as the catalyst for whatever epigenetic changes occur.  If we could figure out the mechanism behind the Feynay effect, it would be a huge leap forward in developmental biology and genetics, as it will likely expose a whole host of areas where the external environment of the uterus shapes the fetus inside, irrespective (to a degree) of their genetic code.  Maybe we aren’t heading towards a GATTACA dystopia after all.

*Of note: the probabilities relayed in the video concerning fraternal/identical twins and homosexuality are identical to those observed with left-handedness and hair whorls and to the predictions of the Klar model.



  1. […] our coverage of evo-devo and the gays, I want to highlight the recent inquiries into the use of prenatal treatment of steroid […]

  2. […] origins of homosexuality* (and the evolutionary accounting for the same) are a popular topic in these parts.  My preferred hypothesis is a mix of neurological genes and prenatal hormones for the former and […]

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