I read as much as my head could handle, so if I missed someone else making the points I am about to, I apologize.
1) Mankind has been hijacking religion and manipulating it to control and subvert the masses for as long as there have been humans walking the earth. A favorite tactic amongst the thumpers is to cherry pick scripture to prove whatever. Here is but one telling example of thousands: "Children obey your parents." If you went to a Christian church as a child, you heard it, over and over and over. What most don't realize is that this pillar of good christian parenting is an incomplete instruction. Those who quote it never continue with the second part: "and parents do not anger your children, lest you turn them unto darkness." The complete verse paints a different picture than the partial one most of us had crammed down our throats.
2) I challenge anyone to find anywhere in the canon, a condemnation of homosexuality from the divine. Neither God, God's child, nor the holy spirit is ever heard to say one word against homosexuality. The only such scripture is in Leviticus, which was and is a handbook of sorts for the Priests. It is a human that says, "when a man layeth with another man, as with a woman, it is an abomination." Again, it's what is left out that makes the difference. The verses before and after the oft quoted portion all deal with what is proper behavior within the sanctuary on a day of worship. In plain language, what is basically being said is, "Hey, no buttfucking in the pews on Sunday." From this passage we are told, quite erroneously, that being gay is an "abomination". Twisting scripture to exclude and condemn an entire group of people, all of whom are just as much "God's Children" as those doing the condemning? Now that's an abomination all it's own.
3) There are no genes governing gender preference. None whatsoever. Current theory is that hormonal antagony within the womb informs gender preferences for the fetus. We know that there are many examples of same sex sexual dynamics all across the planet. Nature doesn't seem to care if anyone's gay or not. There is no law or theory that says everything that happens has to be for some kind of evolutionary purpose. Nature itself seems to enjoy diversity. Human beings looking to validate their own prejudices will cling to whatever is available to justifty their views. Anything is preferable to having to admit being wrong. Spiritual belief or non-belief, and what anyone does with their sex organs are personal matters that are really nobody's business. Why we as a society spend so much time on these private issues is beyonnd me. Are we so insecure that we have to force belief and practice on each other, so we can feel better about ourselves? When will we evolve beyond that? The sooner the better.