Well, again, it is just a hypothesis. Also "happening for long enough" isn't necessarily how it works, for all you know it could have happened during a brief period and remained vestigial, assuming it even happened.

Being attracted to body parts is a fetish. I'm using a neutral definition of fetish, there is not an intended negative connotation. Research shows that the only thing that's like, universally a turn on for people regardless of cultural context is people having sex or masturbating.