You have no facts, you have speculation. That should be the end of the discussion, shouldn't it? But you're so stubborn, for some reason.
As someone who actually works in a university setting, where I have to wade through academic papers constantly, I'm well aware of the speculation and verbal hot air that these types of things breed. If you could find any study that was somehow ignored by the mainstream press and proves something as factual basis for sexual orientation being a product of prenatal origin, by all means get it.
The inherent problem with scientific study of "gay brains" (or whatever) is that the definition of homosexuality, as you've recently discovered, isn't a black and white issue. Scientific research of "gay brains" would be relying purely on the shaky grounds of categorization based on impossible to prove backing and speculation. (i.e. what if a person claimed to be gay, but actually had feelings of heterosexual attraction at some point?) Self-identification is not viable information. And naturally, speculation is entirely irrelevant, because that would be research based on sexual behaviour, which is different from sexual orientation, or identity
But if you can find studies that get around these issues and can offer more than academic masturbation and hot air, then I'll gladly read them.
After 4 years of a biology undergrad degree (with a focus on ecology, so I'm not an expert on endocrinology or neurology by any means), I should hope I'm well aware of the way scientific research works.The fact that you cite the mainstream media as any type of reliable barometer for the validity of scientific research is laughable. This is the same media that heralds every new study on cancer research as a "cure for cancer" and treats the subject of evolution like it's some sort of contentious debate in the scientific community.
For one, I "recently discovered" nothing about that. I was well aware that there was a continuum of bisexuality between exclusively heterosexual and exclusively homosexual. Secondly, are you seriously claiming that self-identification is useless in this case? There is going to be some error associated with self-identification, but when a statistically-significant
difference in brain structure between the self-identifying heterosexual group and the self-identifying homosexual group has been reaffirmed in many studies, you can't just ignore a massive sample size like that. If it is safe to say that the self-identifying heterosexual group is statistically more likely to contain people with a heterosexual orientation than the self-identifying homosexual group and vice versa for homosexual orientation, then these studies are very valid. Aside from brain structure (which it appears you've already read at least one paper on), there are also numerous other morphological differences between people of homosexual and heterosexual orientations (http://en.wikipedia....n_and_gay_women
). All of the bullets are cited with the papers in question. This degree of dimorphism is a good indicator of genetic or developmental differences.
In addition to morphology, you can also look at the influence of fraternal birth order (see Sexual orientation, fraternal birth order, and the maternal immune hypothesis: A review, by Boegart and Skorska (2011) for a good review of this and check out their citations). Multiple studies have shown that the number of older brothers positively correlates with probability of homosexual orientation of the male in question,
independent of year of birth, age, socioeconomic status, and whether or not the boys were raised in the same household. This points to pre-natal influence on sexuality by the mother (supported in the review paper nicely).
There are also epigenetic factors. Bocklandt et al. (2006) found that "the number of women with extreme skewing of X-inactivation was significantly higher in mothers of gay men (13/97=13%) compared to controls (4/103=4%) and increased in mothers with two or more gay sons (10/44=23%)". Differences in genetics are also correlated with differences in sexual orientation (eg. A linkage between DNA markers on the X chromosome and male sexual orientation by Hamer et al. (1993)), but not strongly enough to single out any gene as "the gay gene" (which may not exist).
None of this discounts the possibility of environmental influences on sexuality, obviously, but it's pretty clear that prenatal influences play at least some role in sexuality.