Introduction
Nahor is a son of Terah and brother of Abraham and Haran, who, unlike Abraham, did not journey to Canaan but remained in the region of Haran in Mesopotamia. His marriage to his niece Milcah, daughter of his brother Haran, produces the family line that, a generation later, gives Isaac his wife Rebekah and Jacob his wives Leah and Rachel.
Note: this Nahor, son of Terah and brother of Abraham, shares his name with his own grandfather, Nahor son of Serug, an earlier figure in the Genesis 11 genealogy; the two are distinct individuals.
Family
Marriage to Milcah
Genesis 11:29 records that Nahor married Milcah, daughter of his brother Haran, making her also his niece, a marriage within the extended family consistent with the broader pattern in Genesis of the patriarchal line marrying close relatives rather than outsiders.
Family connecting to Rebekah and Laban
Nahor and Milcah's descendants include Bethuel, whose children are Rebekah, who marries Isaac, and Laban, whose own daughters Leah and Rachel later marry Jacob, making Nahor's branch of Terah's family the source of wives for both Isaac and Jacob across two generations, and keeping the covenant line married within Terah's extended kindred.