I have been taught that the “sons of God” mentioned in Genesis 6 were fallen angels. These fallen angels mated with human women and produced children. If this is true, why did they not continue after The Flood? Also. if they can reproduce, why then can’t faithful angels in Heaven? One more thing, I’ve been told there is no sex in Heaven. If demons can have sex, why can’t humans in Heaven?
All the children of fallen angels perished in the Flood. But there were later attempts to contaminate the Human Gene pool. The Israelites ran into various strains of Nephilim in conquering the Promised land. (Num. 13:33) The sons of Esau and Ammon were also tasked by the Lord to wipe out the Nephilim in their lands (today’s Jordan). And it’s not so much that angels can’t have sex, Genesis 6 proves they can. It’s that they don’t. Eternal beings don’t need to procreate. The same will be true for us. (Matt. 22:30)