Animals are not rational like humans. Even some of the smartest creatures, Orcas, don't really slap seals into the sky because they're malicious. It's just what they do. So some animals are pretty incredible and can actually change their genders if it's necessary to reproduce, and many organisms reproduce asexually, which means they don't need to have sex to reproduce. Unfortunately, humans, like the majority of mammals, do not have these abilities. Being sexually attracted to the same sex is contrary to how God intended and unnatural because of that.
Also, I've never heard of a homosexual animal.
