Warning, there are spoilers to all 7 movies... Rey's parents have been theoried on before the movie even premiered. I have 4 theories that are possibilities.
Rey could be looks kid, but many others think different. One Jedi rule is not to love, or it will create fear, and that will lead to the dark side of the force (As seen with Anakin). A lot think Luke wasn't aware of that rule or it was not used after Anakin's transformance. Another reason would be that in episode VII, R2 is asleep until Luke returns, and Rey never actually in the building that R2 was in for a while, and when she finally got there, R2 woke up right away. She is also very good at flying planes like Anakin and Luke. Yet, Luke did not enjoy growing up on Tatooine, and he wanted to leave, so Luke would never leave his own daughter there to have the same experience.
Han and Leia are also possibilities. First of all, Rey knew her way around the Millennium Falcon. Also, Ben and Rey have the same letter count in their first given name. And the Millennium Falcon was left on Jakku with Rey. Of course Leia would ever leave a child on her own, but she probably thought she was safe. But, Han did state in The Force Awakens that someone had stolen the Millennium Falcon, so that would be why it was on Jakku and it was a coincidence. Also, Leia would have at least remembered her own daughter, unless… Kilo Ren played the trick : "These are not the droids you are looking for", but that could have been before he knew the force.
Could Rey be a Kenobi? It is possible. First of all, when Rey has that vision, Obi Wan seems to say "Rey". Yet, Obi Wan would be way to old to have a daughter, or she would be Luke's age, unless… He had a grand-daughter. But still, Mrs. Kenobi was never mentioned in any of the movies, and .J.J. Abrams would at least have more of a hint, but, Obi Wan did say Anakin was like a 'brother' to him, so he could claim to be a great-uncle. Sadly, Obi Wan is most likely not related to Rey, witch probably let down a lot of people.
Just like Anakin, Rey could have been a not-related-to-anyone-special kind of kid. What I mean is Rey doesn't have to have someone special related to her, but that would be very strange, because she didn't need training in order to use the force.
Ok, thank you all so much! Please tell me who you think Rey's parents are! More theories soon to come :)