Since were in the realm of hypothetical, I would like to ask you a question.
If we manage to identify homosexuality as a genetic disorder, and we determined that there was a 99.999% chance that your children would be homosexual, what would you do?
Would you mind elaborating more on this? It's hard to tell if you mean "avoiding sexual misconduct" as "don't rape, don't have sex outside of marriage" etc, or as "gay men must live as if they were straight". From a Buddhist perspective, the first choice seems reasonable, if a little restricting, since it's a rephrasing of the Third Moral Precept, but the second seems far too imposing on somebody else.
A related question would be - would you have kids if under the same scenario conditions - there was a 100% chance they'd drop dead at age 10? Or 5? That potential child has a chance at life and everything wonderful and terrible it entails but not in any way that you conceive it. You'd think it horrible but maybe they'd feel grateful for the chance. Maybe they'll be the first 10 year old to cure cancer.
It's not the same thing but for it gets at the spirit of it. I mean, my child will have different problems then me. Heck, they might not even view things that I see as problems as problems. It's still my responsibility to raise them to live the best life possible as I see it and then to give them the chance to do that.
So without that- no contracts, no law, no real society - this is why people instinctivly yell for better morals when corruption is detected. Pressure on the outliers creates more contract-caste-conscripts. Problem solved.
It seems more fair to me if I bear the burden of my moral framework, given the proposed determinism.
Of course, this is sophistry; ask about whether two celibate gay men would be allowed a Catholic wedding and the answer will be no because they can't have children, nature of marriage, yadda yadda. Ask whether a man or woman without intact junk can get married and suddenly it's love that is really important.
I still think it's a pretty fair generalisation of traditional Christianity and the vast majority of Christians (liberal western Protestants are a minority on the global scale, and even they don't universally accept abortion and contraception, take for instance Pastor Anderson)