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What I've always wondered, on a bit of a seperate note, is what makes gay people gay in the first place. I mean I personally am straight. But why am I? Why am I not gay? What makes me different from a gay person or vice versa? Is it some form of bizarre natural selection? The species's way of making sure we dont overpopulate by making some of us not want to reproduce naturally? Is it a genetic disorder? Is it nothing to do with biology and simply a lifestyle choice? Ooooh it makes me wonder!
You'll have to keep on wondering because nobody knows.
It seems extremely unlikely to be a lifestyle choice for several reasons:
1) It's not a lifestyle.
2) If it was simply a choice, why would anyone choose it? It's not so bad today, but in the recent past it was something you had to hide completely or face jail, maybe chemical castration, maybe a mental hospital. A bit further into the past and you could be executed for it. But some people were homosexual anyway.
3) Nobody recalls choosing their sexual orientation. Do you recall choosing to be heterosexual? There are some people who are bisexual and choose only heterosexual or only homosexual sex/relationships, but they're not choosing their sexual orientation.
It might be biological without any purpose. Natural selection isn't planned for efficiency - things can hang around regardless, especially if they're in some way connected with something that would be naturally selected. Consider, for example, sickle cell trait. Very useful if you inherit it from one parent only and malaria is common in the area you live in. Will kill you sooner or later if you inherit it from both parents. Maybe homosexuality is caused by a particular combination of variations of genes, e.g. matching 4 results in increased fitness (in evolutionary terms, i.e. an advantage in breeding) and matching 3 results in homosexuality. Or maybe not. Nobody knows.
Why are a similar number of people left-handed? Nobody knows that either, but far fewer people care.
And for the record. Not homophobic!
It's a shame that you have to add that when all you've done is ask a reasonable question in a reasonable way, but you're right to do so. There's irrational prejudice on all sides, as there usually is.
Like you seem to be, I'm interested in the answer purely out of curiosity. Just like I am regarding left-handedness and ambidexterity and various other things that aren't really important (although handedness is far more important than sexual orientation because it's genuinely relevant to many things).