Were all the descendants of Cain killed in the flood?

[tonychanyt]

I doubt it.

There were 8 generations from Seth to Noah (Gen 5). There was no guarantee that Noah's mother, grandmother, great-grandmother, and so on were not descendants of Cain. Furthermore, mixed blood could have come from Noah's wife or his 3 daughters-in-law. Any of these could carry Cain's genes.

 

[Bumble Bee]

I suppose it would possibly depend on how many children Adam and Eve had, and the lineage of the women in Noah’s family.