Genesis 25:2

How could Abraham have children naturally here when years before he needed a miracle to have Isaac?

PROBLEM: As early as Genesis 17, Abraham “laughed” when God told him he would have a son (Isaac) by Sarah, since he was “a hundred years old” (v. 17). But here in Genesis 25, many years later, he has children by Keturah, the wife he took after Sarah died (vv. 1–2).

SOLUTION: There are two possibilities here, either one of which would explain this difficulty.

First, the Genesis 17 text does not say Abraham laughed because he knew he was too old to have children, but because Sarah was past childbearing age (cf. 17:17; 18:12). There was no sure way for a man in ancient times to know he was no longer fertile, as there was for a woman when her periods ceased. Since Abraham was only 100 here, and he lived to be 175, it is reasonable to assume that he was still fertile. By comparison, men who live till 80 today are still fertile in their 60s.