Rey's parents are not in Episode VII. Well. Perhaps there is some credence to the Obi-wan story, but I just don't see him getting it on with some hotty on Tatooine. It seems anti-Jedi like.
Luke was probably pretty popular with the local ladies being able to take down womp rats in his T-16 and what not. He may have had some offspring roaming about Tatooine that he didn't know about.
This seems to make the most sense - being Luke's kin. "That lightsaber was Luke's, and his father's before him. And now it calls to you."