The troll is real.
Corolation does not equal causation. There is no actual proof that it is a mental illness, there is in fact proof that it is not. You have sided with the, "I'm going to believe my opinion because it makes sense to me" side which is foolish. Just as you have made the corolation that humanity requires the opposite sex to get together to reproduce, I could make the argument that we have over-populated the earth and Homosexuality is natures way of halting reporduction in order to sustain the planet. That would make it as natural as it can possibly get.