Brains and Sexual Orientation

There's one group who provide positive proof that a cross-gendered sexual orientation sometimes has a neurological cause. That is, kids whose behaviour from an early age is typically cross-gendered.

I've been unable to find good data about sexual orientation in later life for the transsexual kids who exhibit cross-gendered behaviour early, but suspect they all grow up to be straight, the classic "primary transsexual" described by Benjamin, just as the non-TS kids who exhibit similar behaviour grow up to be gay. And that's the majority of them. Only 1 in 3 of such children are transsexual. Moreover, most women with CAH syndrome, while tomboyish in early childhood, appear to be mostly straight in later life. So our understanding here is limited.

This may help though. From the LA Times :

The brains of gay men resemble those of straight women, according to research being published Tuesday that provides more evidence of the role of biology in sexual orientation.

Using brain scanning equipment, researchers said they discovered similarities in the brain circuits that deal with language, perhaps explaining why homosexual men tend to outperform straight men on verbal skills tests -- as do heterosexual women.

The area of the brain that processes emotions also looked very much the same in gay men and straight women -- and both groups have higher rates of depressive disorders than heterosexual men, researchers said.

The study in Proceedings of the National Academy of Sciences, however, found the brain similarities were not as close in the case of gay women and straight men.

Previous studies have found evidence that sexual orientation is hard-wired. More than a decade ago, neurobiologist Simon LeVay reported that a key area of the hypothalamus, a brain structure linked to sexual behavior, was smaller in homosexual men compared to heterosexual men.

The latest study, led by Ivanka Savic of the Karolinska Institute in Stockholm, was significant in that it looked at areas of the brain that have nothing to do with sexual behavior, suggesting there was a basic biological link between sexual orientation and a range of brain functions.

"The question is -- how far does it go?" said Dr. Eric Vilain, who studies human sexual development at UCLA and was not involved in the study. "In gay men, the brain is feminized. Is that limited to particular areas or is the entire brain female-like?"

Vilain said his hunch was the entire brain was not feminized because "gay men have a number of masculine traits that are not present in women."

The area under study is different from the ones Dr Veronica Drantz has so much evidence about, and I refer readers to her excellent presentations.

A group that is anomalous is one of particular interest to me. Trans people who transition late in life. Because 1 in 3 of those have their apparent sexual orientation change. Are they actually bisexual, and suppressing one attraction for psychological reasons - one before, the other after? Maybe not, for about 1 in 10 (we think) are apparently gay (attracted to men) while looking male, and lesbian afterwards. Or the reverse. It's far more common though to appear to be straight before, and straight after, transition. It's just that the definition of "straight" reverses polarity....

My problem though is that I'm in this group. Ok, IS rather than TS, but here that's probably irrelevant (though may not be). If my apparent reversal of polarity is psychological (or mainly so), as is very plausible, then I'd be probably be psychologically incapable of being sufficiently objective to make judgments about that.

OTOH... it could be that the very common 6-9 month delay after orchidectomy (or similar incapacitation of gonads) before change of orientation reflects physical changes in the brain, possibly due to the cessation of cross-gendered hormones and anomalously increased receptors for the correct ones.

This could be tested by having MRI scans as in the Swedish experiment, during the process of transition. See what effect the hormones have on neuroanatomy, comparing TS people whose orientation changes with those that don't. Getting a significant sample size could be a problem though, as you can't tell who will switch and who won't. Or at least, I couldn't, it was a vast surprise to me when I changed from asexual/lesbian to sexual/straight. Not to others though, it was one prediction that the psych I saw thought was likely at the time - but didn't tell me till after it happened, so as not to bias the result. Score one for the psychological theory.

Of course there might be different causes for the same effect, or both causes could play a part, as could the departure from cellular receptors of various neurotransmitters.

I think I'll have to leave that to other researchers though, as there's evidence that I'm incapable of seeing things clearly here. I must recuse myself.

This is one time where I'll just have to let my instincts guide me, to accept things regardless of cause, and lie back and enjoy it. Hmmmm... that doesn't seem too bad a fate, come to think of it. And I wouldn't be thinking of England either.