All things are genetic, not in that genetics predetermine what will be, but that genetic predetermine what can and cannot be. However, that only means that humans who can be homosexual do not carry genetics that forbid homosexuality. A parallel is that a cat can't do calculus because genetically it lacks the facilities to learn calculus. Note that actually learning the calculus is still environmental were it genetically capable of doing so. In so far as this, homosexuality is environmental - or at least the genetic predisposition accounts for a relatively negligible portion of the sum. There may be men and women who do not carry genetic combinations that allow them to, environmental situations aside, develop homosexuality, but statistically speaking, most people will carry the genes. It's the same with many psychological 'disorders' which are the result of genetic predispositions filtered and shaped by events the human is not most suited for. Many of these disorders are then the result of being forced to not respond to something in the most natural way. (They do however, occur much stronger in people with certain hormonal conditions or brain chemistries.)Furthermore, many of these 'disorders' are symptomatic of necessary adaptation or more often the attempt to adapt and failing to do so. Homosexuality might be the first, a healthy release adaptation to cope with an unhealthy situation.

Rather than looking at it from a psychological perspective, I've also considered homosexuality historically. Even religious texts give some indication about where it occurs that most. That is this, homosexuality seems to be recorded most prolific in not small tribes, but large crowded cultures, particularly among the upper class, and as the religious like to point out, particularly prior to decline. That does not, however, mean that homosexuality is a cause of decline as some of the more frothing-at-the-mouth religious leaders like to suggest before humbly piling on some more wood to fuel the gentle flames of soul cleansing fire. In fact, it's more reasonable to suggest that some of the same social conditions that exist in a society at those stages prior to collapse are such the homosexual lifestyles help to cope with with the problem. Perhaps only on an individual basis, but equally possibly on a social basis.

Why? There are tons of possibilities, but it comes to mind that in a stagnant society, population growth encourages upset and potentially, revolution or collapse. All the contributing and related details to this are far too much to go into, but taken as a whole it impresses upon me that homosexuality is one of many social adaptations that can contribute to stability. Other common adaptations are smaller families on the same scale, and imperialistic tendencies on a large scale. The first is a most common occurance, especially among upper classes which reduces growth. (Upper class families in Western culture tend toward having 2 children which is zero pop growth.) Imperialism expands borders and can relieve, even prevent, stagnation while aggresively pursued.

Of course, it's possible that homosexuality is just a psychological aberration, but I prescribe to the thought that it occurs for a reason, probably a valid reason, and that correcting the reason is important, whereas directly 'correcting' homosexuality may in fact, simply be replacing a good (or at least mostly harmless) social adaptation with a bad, perhaps dangerous one.