You don't have to go outside of our own species to see societies that accepted, and even admired homosexuality and homosexual acts. The only reason people see homosexuality as a stigma now is because of the Abrahamic religions being the dominant religions in the world, and they expressly condemn it.
There were native American tribes that fully accepted homosexual behaviour, and assigned the gay men "women like" responsibilities. Often they were a leader among the women, and often took a husband of their own. Fully accepted, fully integrated and useful.
There are other tribal societies that taught boys they needed to "receive strength" by ingesting the semen of the most powerful warriors in the tribe.... and the boys jumped at the opportunity... lol
Just sayin', if anyone wasn't explicitly taught that being gay was wrong, then no one would think it was wrong.... and people ceasing to believe it's wrong isn't magically going to make anyone turn gay. It's like the odd adage about drug legalization;
If all drugs were legalized tomorrow, how many people would go on a crystal meth bender until they died? I'm guessing if you weren't inclined to do it already, you wouldn't go out of your way to try it.