Gayness is a behavior. It's a voluntary behavior. There's no such thing as an arsonist who doesn't light fires.
No one would want to indulge in the behavior if they did not have a pre-existing inclination to do so. If a man gets horny upon contemplating other men, he is gay already before indulging in any homosexual acts.
There's no such thing as an arsonist who doesn't light fires.
There are some people who get sexual pleasure from lighting fires. There is already something wrong with them before they become arsonists.