Ben was the son of Han and Leia. You never know.
Well take for example that Rey wasn’t really trained by Luke in Ep7 and even before that she was fighting Kylo out of the blue and defeated him. Not knowing how she did it. That’s lame that everyone before needed training from a master and here comes this girl who does it automatically. This is the kind of stuff that irritates me about Abrams and Disney’s cheap way out of everything SW