Those who study the etiology of sexual orientation know that genetics is not fully responsible for whether or not a man is gay. Other factors which are hypothesized to play a roll including either biological conditions (e.g. in utero hormone levels), natural environmental influences (early childhood infections), psychological influences, and many others.
But the results of twin studies have long since indicated that for at least some gay men, part of the causation of their orientation is due to genetics.
However, evolutionary biologists have been uncertain as to why this would be. Knowing that men who are primarily same-sex attracted and not opposite-sex attracted are less likely to reproduce, what evolutionary advantage would these genes have and how would they have carried for millions of generations without dying out?
One theory is that the advantages of having a small number of men without children of their own would be adequate to advantage the shared genes of their siblings, “super uncles” as it were. Now it appears that at least one study provides some credibility to that idea. (Montreal Gazette)
Interestingly, the study was conducted by someone who set out to prove it wrong. Paul Vasey, associate professor in the University of Lethbridge’s department of psychology, went to Samoa to study the fa’afafine [men who were raised female] to provide the conclusive evidence that the “super uncle” theory could be discarded. He found the opposite.
Researchers conducting similar studies in the U.S. and England did not find any supporting evidence for the theory, said Vasey. “So I thought, ‘Well, I’ll do it in a non-Western culture and chances are I’m going to find exactly the same results and it’ll be the nail in the coffin for this hypothesis,’” he said.
Vasey found that the fa’afafine said they were significantly more willing to help kin, yet much less interested in helping children who aren’t family — providing the first evidence to support the “kin selection hypothesis.”
It would be ill advised to draw too many conclusions based on this one study. And directly equating of fa’afafine to gay men in the West is a rather large leap.
However, this does provide additional data to inform the ongoing question as to why some people find themselves attracted to the same sex and others do not.