Misunderstanding Genesis

Misunderstanding " Genesis" When I get to thinking about man about women I think to the beginning of time which is a question in itself bring me back in time to Adam and Eve who lost the Paradise due to a sneaky snake and the bite of an apple off of the tree of life. don't mistake me for a non-believer just analytical you can accuse me of that because if Adam and Eve, the only two on the planet, had Cain and Abel "who" laid down with "who" to create the multitudes? That's all.... simple question. one brother killed the other. "free will"? maybe I'll read it again I must have missed "something" Barbara Suen 4/15/16