In Chapter 4 (26 verses) we find the sad story of the two first brothers (Kain and Hevel) where jealousy prevails and leads to murder. Adam and Eve the first couple bear another child, (Shet) and the family of men spurns. In verse 7 a profound sentiment: "Whatever you do!" says God to Kain, "sin tempts you and attracts you wherever you are, it's for you to control your sinful desire!" When Kain kills his brother Hevel -- he suffers life-long punishment, but his life is spared (God seems against death penalty).
32 verses. Most of the people lived around 900 years plus, and bore children at age 70-100 and higher. Women are not mentioned. The ancestry comes down from Adam to Shet (not to Kain).