I can hardly call it "new", since any available sources seem to be about 4-5 years old, but I can't recall anyone ever bringing this up here before, so I figured why not.
Since the dawn of psychology, the general theory surrounding paraphilias was the brain sort of classically conditioning itself to associate something with sexual arousal, so the presense of a fetish would be like a pavlovian reaction.
But some new(ish) research posits that it might actually be tied to disturbed lateralization in the brain.