1) sexuality is a very plastic thing, so whenever we use the word "gay" or "straight", it should be understood that were speaking about a
of sexual attraction, rather than something that is incontrovertibly "fixed" in the DNA, brain, or what have you.
This has been suggested by many different types of studies, but I would say the brains capacity for reconnecting and rewiring itself, whats popularly
called "neuroplasticity", contains the best evidence against the sexual determinism crowd.
People who are "gay", indeed are likely born that way, that is, born with the built in bias to be attracted to members of the same sex. This is how
it works (as far our sciences currently understand). There's an area in the hypothalamus called INAH3 - a bundle of nerve cells - which seems to
handle human sexual preference. It's homolgous with an area in the rat hypothalamus called the SDN-POA. It's been observed that INAH3 is slightly
larger in males than in females. It turns out, gays have an INAH3 intermediate in size between males and females. This may imply a "inclination"
towards attraction towards other males (the same has been observed in lesbians).
This would appear to suggest that homosexuality is "hardwired", no? Not so fast. We know that London cab drivers have an area in the hippocampus -
which deals with spatial memory - that is larger than average. This may be due to the thousands of streets that they have to commit to memory. Thus,
it appears that the brain changes in response to experience. This is referred to by Neuroscientists as "Experience Dependent Brain Development", or
EDBD for short.
Psychiatrists and psychologists working with gay youth who want to change their sexuality (so called reparative therapy) have had marginal success
with certain VERY motivated subjects who claimed genuine feelings of heterosexual attraction.
Here's how I interpret the evidence. Homosexuality is reversible (same with heterosexuality), but it is enormously difficult. Some developmental
psychologists theorize that homosexuality results from the emotional tension and anxiety surrounding sexual identity in early life. This "tension"
becomes focused as sexual attraction towards the same sex during puberty. In other words, a person who wants to "change" their homosexuality has to
work through this great wall of emotional baggage surrounding their sexual attraction - something that is not easy.
Additionally, the brain will probably always retain a memory of homosexual attraction. "Reparative therapy" at a neuroscientific level, is synapse
pruning. The years spent experiencing this attraction, and finding yourself somehow feminine in certain ways, sculpted a brain that supported this
functioning. To undo it would require a force of will that frankly doesn't exist.
So while you CAN experience genuine heterosexual attraction, if you're a homosexual, you never completely outgrow your previous homosexual
attraction. At most, you can aim for bisexuality.