I had a long idea that I wanted to share, I don’t know if it makes sense, but what the hel…
What if Rey turned out to be something created by Palpatine from Luke’s hand?
Then Rey would be at the same time Palpatine’s “creation”, “daugther”, Skywalker by blood and nobody, because she would have no family and her parents would be the scientists who took her and hid her to keep her safe.