I see where your coming from but the fetish you mention such as "fat women" or for eg. "women wearing leather" can still be considered a fetish because people are sexually aroused by other factors associated with the subject of their desire. But the key word in your example is "women" and women are not festishes and any attraction felt towards them is considered a sexuality.

I don't consider my attraction to boy's a fetish but I do consider my attraction I have to boy's feet as a fetish. I guess my point is the core of your desire feels more like a sexuality and anything you find arousing associated with that core subject matter is more like a fetish. Maybe I'm wrong.

But your right about the fact that "nurture also plays a substantial role" as does predetermination, but we seem to understand a lot more about predetermination than we do about nurtured attractions and sexualities.