Well if you've entered this thread after reading the title, you can't complain, articles with spoilers have been online since before the public debut screening. I just went back and read the ones I'd bookmarked.
OK, so a big point of debate is around Rey's parents, or even possble lack thereof. Was Kylo Ren telling Rey the truth that her parents were nobodies who sold her for drinking money, or was he just trying to get in her head? How would he know anyway?
Here's what I think. Every hint about who her parents are in the movie screams that she's certainly not related to the Skywalker family in any way. The Cave of Evil 2.0 shows shadows and then her own reflection when she asks who her parents are. Caves of Evil generally show helpful if cryptic information (maybe they should be called Uncomfortable Caves of Cryptic Helpfulness?), so the message is "It doesn't matter" or perhaps even "It's you, like almost literally," suggesting some kind of unconventional birth like Anakin's.
Second clue: We can now rule out Rey being Luke's daughter, between him treating her like she was a random stranger who showed up and now having a rather complete picture of Luke's life which doesn't include settling down and having a kid. That was the last possible relationship she could've had to any Skywalker.
Third clue: The kid sweeping the stable floor in Space Monaco at the end. Now we have no reason to believe that there is anyone younger than Luke/Han/Leia related to the Skywalker family other than Kylo Ren, and here's another kid who has force powers seemingly at random.
So the remaining possibilities are "What Kylo Ren said, or something close to it" and "She's a Force Baby."