In general, the extra-biblical literature agrees the sin that precipitated the Great Flood was a satanically inspired effort on the part of fallen spirit beings who were once part of God’s heavenly hosts (the sons of God. See Ps. 82 )who took the form of male human bodies to corrupt the human race. They lusted after and copulated with humans. And, while these writings are not considered canonical or inspired, they still may contain truth. The angel-hybrid view, or the mixing of seeds view was the view at the time of Jesus and held by the early church until the 5th Century.