So, when a male whose sole desires and conduct are exclusively heterosexual goes to prison and is brutally gang raped, thereafter exhibiting desires and conduct that are homosexual, was he a born homosexual?
No, he is mentally scarred from a violent sexual assault. When a woman who is normally not promiscuous suddenly has one one night stand after another after being raped is she a slut? No, she was sexually assaulted and is suffering from mental trauma.
You cannot make any claims as to choice or biology in behavior when the subject has been through such a horrific experience. There are other factors at work.