I think there are a great number of psychological factors which can cause a person to become either gay...or bisexual. I think it's so bloody obvious that there are, that I don't even know why I would have to say it! ;-)

Now then, are there some genetic factors that can come into play too in some cases? Yeah, maybe. Quite possibly. So?

I seriously doubt that it's ALL of one and NONE of the other in every single case. Seems unlikely to me.

And I don't think there's even any point arguing about it. It doesn't matter. It's a tiny side-issue of staggeringly little real importance, in my opinion.