Shem is the son of Noah traditionally linked with the lineage of Abraham.
Genesis 10 presents a genealogy of Noah’s sons, and Genesis 11 traces the line from Shem through several generations to Terah, the father of Abraham. In that biblical genealogy, Shem is therefore the ancestor through whom Abraham’s family line is presented.
Shem is one of Noah’s three sons, alongside Ham and Japheth. The account of Noah’s drunkenness in Genesis 9 also gives the three brothers distinct roles in a family episode, while the Table of Nations in Genesis 10 associates their descendants with different peoples and regions. These genealogical traditions became important in later Jewish, Christian, and Islamic interpretation.
The name “Shem” is also related to the term “Semitic,” a modern linguistic label historically derived from the biblical figure’s name. That connection does not mean every detail of the biblical genealogy can be treated as a modern ethnic classification. For the question asked, the specific genealogical answer is Shem: Genesis places Abraham’s ancestry in Shem’s line, not in the lines of Ham or Japheth.