Is "Cain" of Genesis based on Sumerian myths?

[Jack Ryan]

From: http://www.fsmitha.com/h1/religion-sumer.htm

Conflicts similar to the Hebrew story of Cain and Abel

In giving their gods human characteristics, the Sumerians projected onto their gods the conflicts they found among themselves. Sumerian priests wrote of a dispute between the god of cattle, Lahar, and his sister Ashnan, the goddess of grain. Like some other gods, these gods were vain and wished to be praised. Each of the two sibling gods extolled his and her own achievements and belittled the achievements of the other.

The Sumerians saw another dispute between the minor gods Emesh (summer) and his brother Enten (winter). Each of these brothers had specific duties in creation – like Cain the farmer and Abel the herdsmen. The god Enlil put Emesh in charge of producing trees, building houses, temples, cities and other tasks. Enlil put Enten in charge of causing ewes to give birth to lambs, goats to give birth to kids, birds to build nests, fish to lay their eggs and trees to bear fruit. And the brothers quarreled violently as Emesh challenged Enten's claim to be the farmer god.

That source goes on to state that the Cain/Abel story may have been added to Genesis as late as the time of the Babylonian exile.