In Genesis 4, the story begins with Cain and Abel, the sons of Adam and Eve. Cain, a farmer, becomes jealous of his brother Abel, a shepherd, because God favors Abel's offering over his. In anger, Cain kills Abel, committing the first murder. After the act, God confronts Cain and punishes him by making him a wanderer. Cain expresses fear of being killed by others, so God marks him to protect him from harm. The chapter also introduces the descendants of Cain and highlights the development of civilization, including the creation of music and tools.