Genesis 30 gives the story of which patriarchs descend from which mothers:
Parents:
Leah: Reuben, Simeon, Levi, Judah, Issachar (mandrakes), Zebulun, Dinah
Zilpah: Gad, Asher,
Rachel: Joseph, Benjamin
Bilhah: Dan, Naphtali
This establishes the first order of precedence and some of the character...