I refuse to buy the lie that someone “is” gay. Homosexuallity is something a person does, not something that they “are”. There are no tell-tale indicators at all except for their actions and their self-delusion that they can’t change “what they are”.
I’ve known, worked with and for and even had the odd gay roommate over the years, in some cases it is what they is, not just what they do.
I think in at least some cases there is an actual hardwiring or brain chemistry component to gay/lesbianism.
Still, I’d bet good money that most of it is imprinting on their first sexual experiences. If a man can convince a gosling that he is mother goose, he can convince a lad that he’s his type.