Why would a person choose to have another person beat them, humiliate them, or defacate on them? People pay a lot of money for other people to do just that, ask a Dominatrix. Human sexuality is linked to the human brain, not the human genome and is as varied as there are people. Some people enjoy homosexuality, some polyamory/polygamy, some enjoy age play, some enjoy BDSM, and others are just asexual.
Anyway, stop claiming people are born gay until you can show the genetic markers that cause a person to be a homosexual. Its a false claim.