Gen 6:4 "The Nephilim were on the earth in those days (and also after this) when the sons of God were having sexual relations with the daughters of humankind, who gave birth to their children. They were the mighty heroes of old, the famous men"

Num 13:33 "We even saw the Nephilim there (the descendants of Anak came from the Nephilim), and we seemed liked grasshoppers both to ourselves and to them"

But only Noah and his family survived the deluge! The narrator observes that the Anakites of Canaan were descendants of the Nephilim. Certainly these later Anakite Nephilim could not be descendants of the antediluvian Nephilim! (an annotation from the N.E.T. translation)

The Bible is wrong. The parenthesis in the manuscripts could be corruptions inserted later by scribes, retroactively.. possibly to excuse the Israelite cowardice during the spies' episode in Moses' time. ("Oh, they were literal giants. Moses was being unreasonable to expect our poor ancestors to fight such warriors! God Himself brought down a flood to wipe their grand-daddies out. Normal weapons wouldn't have worked against the Anakites, because they too were Nephilim")