For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Barry Halloran
We can only speculate about what happened, at the beginning. Be careful: Don`t deceive yourself, with your own theories.
GIDION MUGISHA KANYAIRITA
I think that Seth's wife might not be his sister since it seems to have other people who were existing at that time rather than Adam's family Ge:4:15.These are people whom may harm Cain if Cain would not have God's sign of continuing to live.
Jennifer Henkel
Agreed. But God also gave us deductive reasoning -- common sense.