According to the Seder Hadorot, Balbira and Kalmana were the respective wives and twin sisters of Cain and Abel. Genesis 4:17 states that after he had killed Abel, "Cain knew his wife, and she conceived and bore Enoch". In an effort to explain where Cain and Abel acquired wives, some traditional sources stated that each child of Adam and Eve was born with a twin who became their mate. According to the Seder HaDorot, the wife and twin sister of Cain was named Kalmana, and the wife and twin of Abel was Balbira. In the Book of Jubilees IV, they are named as Azura and Awan.