There is likely a connection with the lightsaber to all the scenes in the forceback, but we can't really discern Rey's parentage from that. I think that it is highly likely that Rey is a Skywalker for 3 reasons: 1. Star Wars is the story of Skywalkers. 2. Who is Luke talking to in the first The Force Awakens teaser trailer when he says "The Force is strong in my family, my father has it, I have it, my sister has it, you have that power too"? (https://www.youtube.com/watch?v=wCc2v7izk8w) 3. Near the the release date of The Force Awakens there was an officially commissioned painting of Rey that had the caption "Rey Skywalker", which maybe later was changed. BTW, on the day of the release of The Force Awakens, the wikipedia page referred to her as "Rey Skywalker", but "Skywalker" was removed the next day. Did they know something we didn't, or were they just guessing?
P.S. Marina Sirtus on Star Trek The Next Generation: https://www.youtube.com/watch?v=xjW-Gvi0NXk