It's a nature vs. nurture issue. The problem with even attempting to define it into a genetic vs. behavioral answer is further complicated by the people trying to define it. Just by even asking the question "Is homosexuality a choice or a genetic predisposition?" cast the one asking into one camp or another. You're either a 'homophobe' or you're an immoral hedonist by choice. Both sides are equally polarized and equally mislead because they aren't encouraged to look for answers, and when they do, the bias of their motivations for doing so become suspect.
So with that in mind, here is the Rollo Tomassi take on homosexuality: Until such time as biologist can empirically prove a 'gay gene' (or genetic combinations that predispose a person to homosexuality), I believe the root of homosexual sexual expression is behavioral. Human beings have a biological need for sexual expression: masturbation is usually the first, then we move on to more complex socio-sexual behaviors. In short, we like to get off. It feels good, it's a stress relief and orgasm (plus the resulting endorphin release) has health benefits.
Sexual behaviors and patterns become progressively associated with environmental prompts, situational stimuli, as well as a multitude of reward/reinforcers and punishments depending upon the social acceptability or unacceptability of the that sexual behavior. That's not to say there isn't a biological aspect to this; when I see a semi-nude woman (conditioned stimuli) I get a hard-on (unconditioned response). My body reacts in preparation for sexual behavior by flushing my system with a ****tail of hormones that increase my heart rate, heighten my senses and gives me an erection. However it's the associations, and prior rewards or punishments, that prompt the biological response. For instance, why do I get turned on by a naked Jessica Alba, but disgusted (physical revulsion) when I see a maggot filled animal carcass?
When I hear homosexuals tell me "I can't help being gay", I believe them. Through any set of circumstances their sexual expression has been reinforced to the point where it has become normal for them - they literally can't help but be gay, because that's what prompts sexual response for them. They also, literally, do not make a choice to be gay; their sexual response was brought about from circumstances that rewarded (or more so than from what wasn't) that behavior. The obvious criticism is that for the most part homosexuality is viewed as a deviant or perverted sexual expression and is discouraged. However it's just this taboo that makes the sexual expression a reward.
As I stated above, sexual release is a biological need. Heterosexual men entering a male only prison population, can and do engage in homosexuality and then resume heterosexual behavior upon their reintroduction to society. Are they gay or were they simply resorting to the only sexual expression they had available to them in their given environment?
What about bi-sexuality? Do bisexuals have only half the genetic material to make them half-gay or has their sexual conditioning been such that they're aroused by both genders?
There are some people born with both male and female sexual plumbing, what gender should they pursue in life? Is this their choice when you consider it's their parents who decide to raise the child as a boy or a girl?
Is gender itself biological or behavioral? This is an issue that Feminism struggles with to this day. If gender is primarily a learned behavior then the issue of being oppressed by design is valid, but homosexuality as a genetic cause is invalid (or certainly less valid). But then women's biology, and the degree to which their innate hormonal differences play (estrogen, oxytocin) and the behavior manifested due to them, in molding their gender must also be taken into consideration.
The problem with asking questions like this now becomes one of polarization. Neither homosexuals nor moralists really want a definitive answer as to whether homosexuality is genetic. The longer it goes unanswered, the longer each has to effect their own agenda. If homosexuality is proven not to be genetic, then homosexuals as an oppressed underclass lose in their bid to make their status a civil rights issue. If it is proven to be genetic, then moralists are forced to reevaluate not only their position on homosexuality, but also their concept of predestination and personal accountability. So it's really not in the interests of either faction to look for real answers. The longer we all remain in limbo the longer they have to try to change minds.
