Sociobiological explanations for homosexuality are not empirically supported.
Male homosexuality is the result of psychological dispositions:
1. Since the psychological structures of males are different than females in respect to their needs in an romantic relationship, both in the initiation and its maintenance, males are either better able to fulfill a male or a female's desires in a romantic relationship, depending on particular psychological disposition. Generally speaking, a male will be best suited for a female and vice versa, but when this is not the case, homosexuality is a possibility. The cause of this is merely a deviation from the gendered psychological mean as biologically and culturally specified for male gender. The cause of this deviation is unclear, but surely it is the confluence of polygenic dispositional and developmental factors. Also, there is also the possibility that a male may be suited for neither sex in romantic relationships, in which case, perpetual celebacy is a possibility, or else exclusive sporadic short-term romantic engagements, depending upon the male's other qualities.
2. In addition to capacity to fulfill the needs of the female vis-a-vis the male's romantic needs, the male himself has his own desires. If these desires are better met by a male than a female, then homosexuality is a possibility. Again, what a male or female may give the male are generally specific to the gender, and so the forms of emotional intimacy offered by each particular gender will be distinct (though somewhat variable, as implied above). Again, as in 1, someone may have needs that cannot be fulfilled by either sex, in which case, the result is celibacy.
Sex is not purely physical or else masturbation would be perfectly sufficient. The presence of a body is not the source of pleasure but rather the source of meanings encompassed by the sexual interaction, which while they heighten the physical intimacy itself, do so through the satisfaction of basic psychological needs. Sex with males versus females is different in respect to this and the needs they fulfill. But perhaps more importantly, it is probably the pre-sexual interactions that fulfill the psychological needs vaguely alluded to above (which are too complicated to talk about; this post is already too long) moreso than the actual consummation.
Of those on the borderline between desiring what males and females can psychologically give, or those on the borderline between being able to offer males vs. females the fulfillment of psychological needs, the process of "finding one's identity" can be more drawn out, with a certain persistent bisexuality the consequence. Those on one end of the spectrum or the other will find it easier to "find one's identity" and so will require less thought in order to do so. Also, identities do change, and people have their "homosexual periods" and then switch to "heterosexual identities," and vice versa. I do take issue with the notion that someone is dispositionally straight or gay. I see it as dispositional with room for movement depending upon psychological development and social context, and I'm supported in this versus a black-and-white perspective.
At some point, many of us wonder whether we're straight or gay, or worry about being gay, and attempt to vitriolically exclude the possibility of homosexuality from the possibility of our identities out of fear of being gay. This is partly what constitutes homophobia, and this is part of the reason that you will find men acting aggressively against one implying they might be gay (though there is also the possibility of social injunction, which is a good reason to deny homosexuality).
How are genetics involved? That is anyone's guess, really. I could probably advance several theories, which would not be traditionally sociobiological. A simple postulation that a highly adaptive and adaptable cerebral cortex that could dispose someone to sexual relations with their own gender is probably sufficient, since homosexuality does not sufficiently counterbalance the enormous success that our cortical adaptability has given us to make this complex cortex maladaptive. Homosexuality could be the reproductive price that some individuals pay for our complex humanity.
I do think the decision of what constitutes one's identity inextricably involves agency, since it is the necessary suppression of other possibly existing identities, of which at various developmental points in our lives we have many. And I would hate to think that anything that I am does not at some level constitute a choice, and this involves my own heterosexuality. According to this schema, then, I think I hold homosexuals to choosing their identities as well. If I was gay, I'd certainly say I chose it. There are homosexual groups who, by the way, take this stance, so I don't think it is a matter of pure disposition vs. choice as the argument is made to be, but rather there are a multitude of perspectives to consider.
