Of course homosexuality is natural, meaning people are born that way. If it was an illness, does that mean that a person can catch gay? And can you cure gay? No. True homosexuality is not a choice, just like heterosexuality is not a choice that you made one day. You can't help who you are attracted to.

And the previous argument that homosexuality is rare in the animal kingdom and that proves that humans are faking it doesn't hold any water. Nice try though.