"Natural" and "Unnatural"
I really hate the use of the terms "natural" and "unnatural" being used to describe things / acts, actions that exist in the real world. It is in my opinion a semantic slight of hand to give a more "objective" feel to moral / judgemental beliefs / statements. To me if something is "unnatural" it simply cannot happen. If it can happen it is "natural". Thus wearing clothes is "natural", so is loving someone, or writing a essay or saving someone from drowning with a life preserver. Of course murder, rape etc., all acts we deem bad etc., are also "natural".
What people almost always mean when they describe something as "unnatural" is that they feel / think that the thing or act described is immoral and / or evil. However talking about something as "unnatural" avoids the objection that the statement is simply a subjective statement of moral belief and hence easily countered by other, different statements of moral belief. Instead it elevates the belief to a more objective "higher" plane of argument that is, superficially objective and hence no longer merely a subjective moral belief.
Of course this type of argument is merely pseudo-objective, but it often achieves its purpose of getting people to discuss whether or not something is "unnatural" rather than the morality or lack thereof of some thing or act. It in fact makes no difference to the morality of something whether or not it is "natural" or "unnatural", but it does create the illusion of objectivity to argue about that and it avoids overtly talking about morality when that is what your in fact talking about. In other words it is a semantic con.
Associated with this is the concept of "natural law". I do not mean things like Newton's first law, or Kepler's laws of planetary motion, which like a real "natural" law are virtually unbreakable but the philosophical notion of "unnatural law", which is nothing more than a semantic trick designed to shroud the discussion of morality and ethics in a pseudo-objective disguise and further import false notions of scientific rigor into the discussion of morality and ethics.
Discussions of whether or not something is "natural" or 'unnatural" are just semantic games to avoid a clear discussion of ethics and morality.