I'm not sure you understand the concepts of 'proof', 'theory' and 'evidence'. There is mounting evidence, and has been for quite some time, of the genetic links to homosexuality, along with all manner of human conditions/predispositions. If you choose to ignore that evidence I doubt I, or anyone else will have much luck in achieving meaningful discourse with you.
The links I posted were the first few of about 58,000 hits on the subject. I totally agree that nothing there is fact, in so much as the theory of gravity is also not a 'fact'.