I disagree that sons of God were angels. I think they were simply followers of God and sons of men were men of this world, non-followers like secularists or atheists.
Has to be! That's how those Giants (Nephilim) were made. Two humans of different religious or political differences got together and...that sexual union creates 8-10' tall (human?) half-breeds with six fingers and six toes. Not long after that God decides to flood the world (there were reasons).
Why would the Bible describe the children of regular human matings as “nephilim”, the same word it uses to describe the Philistine giants? It seems obvious there was something more unusual about the pairings if the writer of Genesis found it noteworthy, thought it important to mention the unusual offspring produced by them, and noted both of those immediately preceding the decision of God to wipe out the wicked men from the earth with a flood.