I don’t really understand why people make such a big fuss over the question of whether homosexuality is something that people are ‘born with’ or whether it is something they choose. I acknowledge that it is a factual question that is interesting to answer, but I don’t see why it is morally significant.
There’s nothing wrong with being gay if it is an inherent part of your biology, and there is nothing wrong with being gay if it is a conscious choice or unconscious response to your experiences and societal context. What makes any kind of sexual activity ethical is the meaningful consent of the participants, not the characteristics those participants have. Similarly, when it comes to the roles couples play within society (including as upbringers of children), I don’t see why sexual orientation has any relevance that justifies different treatment, either socially or under the law.
Opposition to homosexuality seems to be pure prejudice, plain and simple – often religiously motivated. Perhaps that explains something about why people are obsessed with the nature/choice distinction. If you are personally deeply opposed to homosexuality, see others doing it, and believe that it is a choice, you might feel personally bothered or insulted by the choice you think they are making.
Of course, even if you happen to be the parent, priest, or legislator of the person in question, the way they choose to live their romantic and sexual life is really not something you have any legitimate claim to controlling. Other people like things that you don’t. Get over it.