They wanted incarnation. This was an affront to God. And they figured out. Now, these angels couldn't speak into existence like God can, but they participated in creation. They knew at least as much about genetics as our scientists do today. So, what does all of the ancient records say? They came down, they took the genetics of women, the genetics of animals, and created a unique biological entity into which a man's spirit wouldn't be because it wasn't a man. The character of an animal wouldn't go into it because it wasn't a cow. It was something entirely outside of the divine order.