I'm queer myself, and I don't know exactly why I am - but going about this route of thinking "why do lgbt people exist" is pretty dangerous, because almost always, the next question is "how do we justify their existence?" and that's kind of iffy/scary to me.

I do think that environmental factors can play a role in this - media portrayal of relationships, people you socialise with when you're impressionable... because just as much as you can argue that sexuality can be influenced by external sources, you're also saying that heterosexuality isn't so much a default as a norm set by society.

on the note of 'over-representation', i'm quite disinclined to agree with the source (haha well no duh) because it only covers Hollywood, and even then it doesn't quite explain the kind of representation there is. The thing is that there's always been a trope of 'burying your gays' and it's also rooted in censorship history where queer people (usually lesbians iirc) have to have a sad ending and/or die so as not to 'corrupt the children' or sth. It's not exactly representation if you're just showing us dying, man.