I know men who've been happily married (from all outward appearances) who have subsequently decided they were "gay". (In fact, one such just recently died of AIDS.)
There are also many married men who engage in anonymous homosexual sex - cruisin', to use the popular term, at dirty book stores, restrooms, via chat rooms, etc.
The "predisposition" seems awfully like a matter of choice.
My belief is that most men engaging in homosexual behavior do so because of the more ready availability of homosexual sex. Could you tell the sex of the other person when you're doing it through a "glory hole" ? Is it a matter of "attraction" or just a quick orgasm ?
I can't argue your points about married men straying because I've known a couple who have. But when I asked one of them how he could do such a thing (I know him well enough to ask), he told me it was always something that he felt he wanted.
No doubt some may engage in homosexual behavior because it's available.........but I think those are in the minority. I respect your viewpoint on this, but like I said.........either you're pre-disposed or your not.
Of course like someone else said, one could always abstain for moral and personal reasons. That would be my hope for them.