>>510819690 (OP)The majority. Do some googling and you'll find some studies done in the 80's. It was interviewing gay/lesbian people regarding sexual history and then had some questions about sexual abuse.
The studies found that over 80% of gay men, and over 70% of lesbians, had been sexually abused as kids. This research was dropped pretty quickly and is now hard to find. And, obviously, no one is doing these surveys in the modern era.
Additionally, in more fringe scientific research, four genes have been found that some are theorizing dictate sexual orientation. Imagine if these genes could be 'on' or 'off'.
Either the first or second are always on. This results in a heterosexual. If both genes are on, this results in a bisexual. If all four are on, this results in a homosexual.
Interestingly enough, people who are born gay/lesbian only result from two bisexual parents.
Additionally, we now theorize that genes 3 and 4 can be turned on/off with early childhood diet and/or trauma. So someone who isn't born homosexual can still 'transition'.
This also explains the uptick in the increasingly bizarre ways individuals are 'choosing' to identify - give a child infinite internet access, psychoactive pharmaceuticals, and hormone distorting foods and all manner of abominable behavior will manifest.
Feel free to believe this or not, I'm just a guy on the internet who enjoys reading research papers on his spare time.