OP seems to have a general problem defining "change" and how we as humans can observe change. It has absolutely nothing to do with the original premise anymore and therefore I consider OP's further comments to be irrelevant.
I beg to differ on your premise regarding "we can exclusively define what is natural to humans" unless you supply such a definition.
Otherwise why wouldn't using instruments (for example, for a sex change) created by humans be natural means for doing any particular thing for a human being?
fuzzydunlop, it is why it is a "however" and not a "but".
The purpose of the 'however' function is to add something that furthers the argument without supporting or denying it. A good example of this is the other 'however' statement in this argument tree which attempts to further the argument by stating we need a more elaborate definition of natural. Stating that what is natural is not necessarily right or wrong does not further this specific argument because it does not help use determine whether changing one's gender is natural or not. Whether natural things are right or wrong is a separate argument that should be talked about outside of this argument.
Police are under no legal obligation to protect and serve.
Fallacy Of Red Herring
Just because police officers are not obligated to protect and serve does not mean that there are no "good" police officers. Officers can still protect and serve even though they are not obligated to. You have also not supported with evidence that protecting and serving is necessary for being a "good" police officer.