I think there's a tiny bit of truth in there somewhere. Most people are "born straight", but some percentage are born absolutely gay. They may not know it until they reach puberty and begin to have sexual attraction to other people. They may know from an early age. But there are also a certain percentage that are born bisexual. When they reach puberty they can be attracted to people of either sex. If one of those bi people has positive experiences with either same sex or different sex others, and never has any positive experiences with the other sex, they get in that habit. Probably for life. We tend to imprint on our early sexual experiences.
So that would be a case of a gay person "turning" another gay. But that other person was bi to begin with.
Then there are sexual predators who are more predator than sexual. Like the few pedophiles who don't care which gender their victims are. Or the hypersexual psychopaths who rape women on the outside and rape other men in prison.
I left out what you so eloquently described above, namely the acknowledgment that sexuality exists on a continuum rather than on two binary choices.
Thanks for reminding me.
That said, we still wind up back at the old Four Leaf Clover question.
Why haven't four leaf clovers taken over the entire clover population?
Because homosexuality is a deviation from the norm.
It is however, a STANDARD deviation, and by that I mean one which is expected,
and one which contributes important factors, vectors and input to the continuum as it always has.
We might even eventually figure out that homosexuality actually serves a very important purpose in both society and genetics, and we may eventually discover that that perennial five to seven percent of the population who are gay exist for reasons sociologists and scientists have yet to understand.