This may be why the Israelites were supposed to destroy everyone God told them to, including children, when they entered and started posessing the promised land.
Absolutely that's the reason!
That's one of the major reasons why the Sons of Seth theory breaks down. If the Sons of Seth married the daughters of Cain and created a bloodline of giants (at that alone is a silly premise), God would not be seeking the elimination of that bloodline.
That bloodline would have the same offer of Salvation the rest of us have.
What is shocking in 1 Samuel 15:3 is that God commanded Saul to kill EVERYTHING...even the Amalekite animals...
Now go and smite Amalek, and utterly destroy all that they have, and spare them not; but slay both man and woman, infant and suckling, ox and sheep, camel and ass.This makes one wonder if the Fallen were again befouling the animals as they were before the Flood.
There certainly seems to be some spiritual genetics which pollute down through the generations that we understand little about.