Surrogate mothers helped produce the 12 tribes of Israel. Jacob had children by both of his sister wives, Rachel (2 sons) and Leah (6). At their request, he also had sex with their two slave girls —all for the purpose of trying to give him as many sons as possible. “Jacob had…two sons by Rachel’s slave girl Bilhah…two sons by Leah’s slave girl Zilpah,” (Genesis 35:22, 25-26 NCV). Strange and Mysterious Stuff in the Bible, p. 149.