Methylation and orientation: keep 2015
There is a new head scratcher.  A recent article (Michael Balter “Can Epigenetics Explain Homosexuality Puzzle? Science vol. 350 no. 6257 October 9, 2015 page 148) has linked sexual orientation to an epigenetic process.  An epigenetic process of course is any process other than a gene that regulates genes.  What has been done by a group that will be presenting at the American Society of Human Genetics in Baltimore is they have looked at twin pairs in which one member is gay and the other straight.  These are identical twins so of course the DNA, including all the genes, is shared.  If one of a pair of twins is gay the other had a fifty to eighty percent chance of being straight.  So it’s not the genes but something that is switching genes on and off, something that is inherited but not always inherited.  Attaching a methyl group to a gene can alter its function, so at least that is a candidate. 

And of course I am much interested.  Quite possibly homosexuality, or a tendency toward same, is a form of infertility and is part of the infertility that is attendant upon failing to marry cousins.  What they have found, it appears, after an enormous amount of analyzing methyl markers and doing computer evaluations, that there are five regions where sexual orientation is linked to methylation pattern.  Genes for nerve function and immune function have been implicated. 

However they suspect that the mother’s methylation pattern has been erased in one son (these being male pairs) and not the other.  Well they certainly seem to be snapping at the heals of the mechanism.  On the other hand, as seems to by the fashion, they are looking more at methylation as a mass action rather than, as I fancy, a very site specific process.  For me there is no way to explain the demographic data with the mechanism on offer.

I hasten to say that the results so far, they point out, are quite preliminary. 

And of course they make no mention at all of kinship, so their work may be totally unrelated to my own.  Still, it’s nice to know that the hunt is up or at least a possibly related hunt.

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