in the books, Han and Leia had three kids: twins Jacen and Jaina, and youngest Anakin. Luke had one son, Ben, with Mara Jade. Both of them (Luke and Mara) were Jedi, and all four of the kids had mad Force powers. The proscription against having a family ended with Luke--he re-started the whole thing, and things changed under his instruction
In this movie universe, Ben (Kylo Ren) belongs to Hand and Leia and Rey is Luke's child (I'm pretty sure). Hard to believe that Han and Leia would have a daughter that disappeared and they just sort of forgot about her, right? If they go a according to book canon (and no one says they have to, for sure), but with Ben and Rey as cousins rather than siblings, the relationship between them doesn't change much from the books (and the ultimate end will be pretty terrific
. )