Is homosexuality normal?

So I've read out there that homosexual has been proven to be a natural thing, but those articles seem to have very little science behind them and seem to be full of opinionated statements slamming anyone who doesn't accept homosexuality. So that's why I have joined here.

From my experience, I've had two friends who have come out and say they are gay. And there is a pattern in both of their lives.
When I was in the last years of school, my friend and I were pretty cool with one another, and I was one of the first he came out to. He later told me an event in his life when he was younger which likely influenced him growing up to take a liking to the same sex (basically he did stuff with other kids the same age when he was like 7 or something).
My other friend, he got closer to me, because as it turned out I was one of the few of his friends who didn't hate him because of his sexuality. Again, he later explained to me an event in his life that likely changed him (same age and gender cousin experimenting on him at around 12 years old).

Now I am not trying to state anything here, as I know these are just two accounts. But I just want to know if others know of anyone who has, or perhaps they themselves have, been influenced to like the same sex because of disturbing events during their time growing up? Whether people do in fact have homosexual tendencies naturally/from-birth?

Thank you in advance