More fun from Jeff Dugger: A Small Voice FAQ
Many who agree with your stance on Gen. 6 allege that Satan and Eve had sex producing Cain. Do you agree to this teaching? Absolutely not! God's word clearly states that Cain was the product of Adam and Eve (Gen. 4:1). There is no passage in Scripture where a sexual union between Satan and Eve is ever spoken of. Those who promote otherwise speak directly against God's written word. (Our research reveals Satan to be a very frustrated and hermaphroditic entity. Hence, there is hardly any chance at all of Eve ever being able to become impregnated by such a creature. Hermaphrodites don't reproduce very easily according to God's laws of physics.)