Homosexuality does not exist in nature.
First, there is a statement of ignorance. Homosexuality exists in nature. In fact, there are instances that have been observed where certain animals show a preference for the same gender, in and out of captivity.
Can Animals Really Be Gay? | Popular Science
Second. I tire of the "bait and switch" tactic being used in "homosexuality in nature" discussions. A: Homosexuality is not natural. B: Well, that's not true, because it exists in nature, so here is the proof. A: Well then, maybe we should start throwing poo at each other and legalize rape, because these exist in nature too!
So, to clarify this:
Knock it off. The statement that something is "natural' is not the statement that something is "moral". These are two different arguments and what we end up with are circular reasoning and a never-ending debate.
Rape, infanticide, genocide, bestiality, pedophilia -- All of these exist in nature. The existence of this says one thing and one thing only:
These behaviors have a natural basis. It is NOT saying that such things should be considered moral or okay.
So. The argument that homosexuality is unnatural is a false argument, provably wrong and proven wrong consistently through observation and our own genetics. Homosexuality has a basis in natural processes. This is undeniable and irrefutable. Homosexuality is natural.
But, just because it is "natural" does not mean that it is "moral". Any person who debates the case against "homosexuality is unnatural" is not debating the case that "homosexuality is moral". A given thing being immoral or moral is a different issue which can not be judged by the standard of what happens in nature. Other criteria must be used to judge the morality of our actions other than acting like chimpanzees.
I do not hold homosexual behavior to be, in and of itself, immoral; but that basis does not come from the false premise of emulating octopus.