How did the twelve tribes of Israel originate?
The twelve tribes of Israel originated through Abraham's son Isaac, Isaac's son Jacob, and Jacob's twelve sons. While in Haran, Jacob fathered eleven sons: six by Leah, others by handmaids, and Joseph by Rachel. Ten years after returning to Canaan, Rachel bore Benjamin, the twelfth son, completing the tribes.
Les explains that the nation of Israel comes about by Abraham's son Isaac, Isaac's son Jacob, and Jacob's twelve sons, from which we get the twelve tribes of Israel. While Jacob was up in Haran with Laban for twenty years, Leah had six sons herself, and then sons came by Leah's handmaid and Rachel's handmaid, giving 6, 8, 10. Finally Rachel had Joseph, and then ten years after they returned to Canaan, Rachel gave birth to Benjamin, making the twelve, though she died in childbirth. Les notes that these twelve sons will end up down in Egypt.