Wayne T. Pitard, “Before Israel: Syria-Palestine in the Bronze Age,” in The Oxford History of the Biblical World, Michael D. Coogan, editor (Oxford: Oxford University Press, 1998), 27.
There are many reasons to be skeptical of [the Patriarchal] narratives as historically accurate accounts of the lives of Israel’s progenitors. Indications within the narratives suggest that they had a substantial prehistory as oral literature. Modern studies of oral transmission demonstrate that stories preserved in this manner do not primarily serve a historical or antiquarian purpose; rather, they are meant to present cultural values that must be passed on to younger generations. In modern parlance, their function is sociological rather than historical. Usually, historical facts quickly become garbled in an oral tradition, which adapts such information to make whatever point the story is intended to convey. Events and characters are often manufactured for the narrative purposes, and variant versions of a single story develop alongside one another.
Several of these characteristics appear in the book of Genesis.