How the giants came back a second time after the flood is an interesting topic.
Here is a Doves letter about it. And below are my thoughts.
I have noted that a piece of the puzzle might be found when we think about the grapes that the Hebrew spies brought back.I have never heard anyone make any extensive comments about the grapes in Numbers 13:23. Here we read that one cluster of grapes needs poles and two people to carry it. I wonder if that is telling us that they were unusually big. That makes me wonder if the grapes were created by some type of genetic technique by fallen angels. And that makes me wonder if the giants came back by some type of genetic reproductive technique that could be done in a fallen angel laboratory.And the fact that the angels who participated in sex with human women were punished harshly, and the flood was such a great judgment - all make me think that the rest of the fallen angels might not want to attempt sexual relations with human women again.Just a thought.
Mary