The writer of the Books of the Chronicles, probably Ezra, recorded the immediate descendants of Isaac,
“And Abraham begot Isaac. The sons of Isaac were Esau and Israel. The sons of Esau were Eliphaz, Reuel, Jeush, Jaalam, and Korah. And the sons of Eliphaz were Teman, Omar, Zephi, Gatam, and Kenaz; and by Timna, Amalek. The sons of Reuel were Nahath, Zerah, Shammah, and Mizzah” (1 Chronicles 1:34-37).
From so few, came so many. Yet, that should not surprise us, because every human living on the earth today descended from Adam and Eve, and we can even move a couple thousand years toward us and say that every one of us has descended from Noah and his wife.
This text is part of a larger context showing the family of Abraham as descended through Israel, then Judah, then David, and as we move into the New Testament eventually we come to the Christ, Jesus of Nazareth.
God showed that we can identify His Son, and that gives us the right to become children of God.