is HOMOSEXUALITY unnatural......?

No, it isn't unnatural. It's just as natural as heterosexuality. You can say it isn't normal, in in some respects that's true. However, homosexuality isn't a big deal, and it poses no harm to society. The only hindrance to society would be a government attempt to ban homosexuality.

I guess technically it would be natural in a way that people are prone to sin, but unnatural in the way that it's not the way God intended people to be.

Humans are different from animals because of the ability to put a rein on our instincts. Without such a curb, we would also belong to the animal kingdom. For instance, tere are times when one is angry with another person to the extent of strongly feeling like striking or even killing him. If this instinct were to be left on the loose, then it could be imagined how this world would be. Homosexuality is the result of the inability to curb an unhealthy or dangerous instinct. To normal humans, homosexuality is repulsive and irritating. However, to some people, it is a natural feeling. For the latter group, it is incumbent on them to fight off the odd feeling so as not to be like animals. Unfortunately, however, some cases we see outwardly as homosexuality is not so in the real sense of it. Some "men" have female features and hormones running in them, and vice versa for some "women". We even have some with both features running concurrently. This peculiar situations are an exemption that has to be considered before passing a general judgement over all homosexuals. In other words, homosexuality is natural to some people but artificial to most others who have imbibed the ways of the animals.