Born Gay summarises the latest research into the psychobiology of sex orientation, concluding that studies with twins show that around 30 to 50 per cent of sexual orientation is due to genes. The rest is the result of processes in the womb.
The genes involved in sexual orientation produce receptors in the brain which absorb male hormones released by the developing baby's ********** It is thought that in gay men these receptors are less sensitive or are blocked. The absence of testosterone results in the brain developing certain female characteristics, including attraction to men.
According to the researchers, there is much evidence to contradict claims that homosexuality is caused by social factors, such as seduction, or that it can be learnt. "Showing that homosexuality is not due to learning, or seduction, or smothering mothers has very clear implications for social policies," Dr Rahman added.
There you go nature over nuture and another interesting tidbit of the book goes on to say
The hormone may also be responsible for increasing the size of the *****, another extremity. A number of studies have shown that gay men are better endowed than heterosexual men.
http://news.independent.co.uk/uk/this_britain/article296445.ece
So not only is it natural and biological they also have bigger c[b][/b]ocks than your average white male conservative.