This article is making the rounds of mainstream media sites suggesting that there is a physiological basis for homosexuality (link to previous article using this method herehere). The researchers use MRI and PET imaging in combination with exposure to putative pheromones to show that individuals that score a 6 on the Kinsey scale for homosexuality (aka totally gay) like pheromones corresponding to the same sex.

While I have little doubt that homosexuality has nothing to do with choice, having gone through puberty myself and recalling little thought about making a choice to like boobies, this type of article isn't truly of great value. While they show a physiologic response to pheromones, those of us who understand science know that environment and behavior is going to feed back on our brains and even if homosexuality were a choice, which it isn't, there is no reason to expect a PET scan to act as a kind of sexual orientation lie detector.

It's entirely possible, if you believed the ridiculous proposition that people would choose to be gay despite all the hatred and alienation involved, that such a choice of lifestyle and behavior would then allow one to be excited by male pheromones from non-genetic or environmental programming of neural responses. Scientists have to keep looking and find the real origins of homosexual behavior which quite reasonably exist, based on normal variation and other examples of homosexuality in nature, within the spectrum of human sexual variation.

Nothing has really changed since Kinsey studied this 50 years ago, there is a continuum of human sexual orientation, and that is to be expected. The focus should instead be on the genetic basis of this variation, and I'm sure one day through analysis of SNPs and human genetic screening we'll find genes that contribute to a higher probability of homosexual behavior in humans. Studying adult humans' brains isn't necessarily informative in contradicting the bigot view that homosexuality is an evil choice of hellbound souls.

update - Can anyone figure out where this damn thing is published? I'm trying to find the article supposedly published today in PNAS and I can't find it in the table of contents or in AOP.