Ok, explain to me why *you* are sexually attracted to a beautiful woman instead of a man or a tree or a rock. You can't say it's "just natural".
Also, why does a skunk smell "bad"? I mean, its all just chemicals so there's no real reason why one smell should be preferable over another. Why does our brain interpret the smell as bad?
Umm...why not? We are created to reproduce, that's what those organs are used for. To choose not to do so is disordered, you'll see them listed in the DSM under paraphilic disorders. We have natural instincts built inside us, you don't need to be taught to suckle your mothers tit, duck at the sound of a loud noise, struggle to live if you fell in deep water not knowing how to swim. All, including reproduction, are instinctive to the survival of the species, to ignore those traits is disordered and self destructive.
As far as smell is concerned I don't know any animal that prefers skunk smell other that the skunk. There is no "chemical interpretation" made by the brain that causes one to duck when there's a loud noise so I fail to see how your example is anything but sophism. To begin with a flawed premise is garbage in, garbage out.