'Families' in the Bible

You are the sons of the prophets, and of the agreement which God made with your fathers, saying to Abraham, Through your seed a blessing will come on all the families of the earth.

And he made with him the agreement of which circumcision was the sign. And so Abraham had a son, Isaac, and gave him circumcision on the eighth day; and Isaac had a son, Jacob, and Jacob was the father of the twelve heads of the families of Israel.