The statement "homosexuality is unnatural" is arguably an even worse argument against it than the aforementioned rebuttal. Whether homosexuality is natural or not is entirely semantic, and every conclusion you can possibly come to using the various definitions of natural in no way suggests that homosexuality is wrong, unless you also concede that any modern technology is wrong, which I think that we can all agree is stupid. I'm not sure if you said that it's unnatural and therefore wrong earlier, but yeah.