Book of Enoch presents the story of how 200 giants, rebelled against heaven. Then, these fallen angels descended to the plains of earth, married human wives, and fathered the Nephilim.
The union of these angles with women produced 450-feet tall giants (chapter 7:12-15).
I don't really see how giants, even 100 feet tall could have sex with and 8 foot tall human. They probably first used computers too mix the two races first.
