The Book of Genesis
According to the Book of Genesis in the Bible, after Adam and Eve had to leave the Garden of Eden, they began to have children.
Adam and Eve have kids
Cain and Abel have a fight
Cain was very angry, and he killed his brother Abel. So God was angry with Cain, and made him go away and live in a country far away. And Adam and Eve had a third son, Seth. All the Jews are supposed to be descended from Seth.
Why did people tell this story?
This story shows a memory of the beginnings of farming and sheep-raising, which would have been around 10,000 BC. It also shows one of the oldest themes of West Asia, which still continues today: the conflict between the settled farmer and the wandering shepherd, where each considers the other to be bad, and believes that God is on his side.