I think its due to a lack of knowledge that someone can turn round and suggest that homosexuality doesn't occur in the wild.
Macaque females are known for homosexual behaviour as a means of moving up the social ranks.
Bonobos on the other hand are notorious for sex in pretty much every viable combination....
Use your imagination, i don't think details are suitable for this forum.
Either way to claim homosexuality is a product of the supposed human 'condition' perhaps avoids the facts of nature.
Just googled quickly and according to various sites a few of the other animals that engage in homosexual behaviour/practice are;
Sheep, dolphins, various species of bird, giraffes, various sea mammals, big horn sheep.
The list appears to be endless.....