Came across a YT video the other day on nephalim and the book of Enoch. The summary was that the nephalim were breeding with everything on earth, including animals, making new non human monster species and this is why God commanded Moses to completely wipe out the Hittites, Amorites, Cannanites, etc. down to the livestock. Also why He destroyed the earth with a flood because only Noah had kept his bloodline pure.