Exodus continues the Genesis story, with the family of Jacob (Israel) moving to Egypt. Jacob has twelve sons and one daughter, Dinah. Now, in Exodus, the sons are listed as having families.
These are the names of the sons of Israel who came to Egypt with Jacob, each with his household: Reuben, Simeon, Levi, and Judah, Issachar, Zebulun, and Benjamin, Dan and Naphtali, Gad and Asher. All the descendants of Jacob were seventy persons; Joseph was already in Egypt (Exodus 1:1-5).
In time, each family (“household”) grows into a large tribe named after its patriarch, a pattern that continues throughout the Bible (1 Chronicles 2:1-2; Revelation 7:5). Within each tribe, men serve as heads of families and family groups. For example, notice the first census recorded by the book of Numbers.
Take a census of all the congregation of the people of Israel, by clans, by fathers’ houses, according to the number of names, every male, head by head….And there shall be with you a man from each tribe, each man being the head of the house of his fathers. And these are the names of the men who shall assist you. From Reuben, Elizur the son of Shedeur; from Simeon, Shelumiel the son of Zurishaddai; [and so on]…. (Numbers 1:2-7 cf. Exodus 12:37; Numbers 1:18; 7:2, 10; 10:14-28).