The Quran’s version of the story is reflective of the conventional practice in the Middle East (and throughout the world) of primogeniture—i.e., succession by, or preference of, the first-born son.
However, one of the most striking themes of the Hebrew Bible is the clear and recurrent practice, in Israelite culture, of favouring the younger, or youngest son over his older brothers—e.g., Isaac over Ishmael; Jacob over Esau; Joseph and Benjamin over all their older brothers; David over all of Jesse’s sons; Solomon over all of David’s sons—even Abel over Cain (admittedly, they weren’t Israelites, but the Genesis story is).
That said, the Book of Genesis is being a little disingenuous when it presents Isaac as Abraham’s “only son” (Gen. 22:2)—most likely the work of later editors, during compilation of the Hebrew Bible in the Second Temple period.
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(Originally written in reply to a question at Quora.com)
