Interesting take from the "Cliff notes"
I do not see scripture on castration then, I do not see, he raped his Mother and had a child, not literally stated.
Yet it can be construed that way, yes, it can be
Another ? I have when I am placed in heaven after physical death for sure. For now I reckon me dead as in Romans 6:1-12, Acts 17:28
The Nephilim did carry on after the flood as said in Genesis 6. I can conjecture it might have been through the women of the three kids that were the Noah's children's wife's then. Might have been of the Nephilim. So it might be in the DNA, as There were Giants in those days, even after the flood , not so much today! has dwindled down a lot since.
I think you have a good conjecture, me staying careful not to conjecture things out too much and make any other doctrine out of the "Cliff Notes" written in the bible other than the burial, death and resurrection of Son Jesus for us to be new in Father's Spirit and Truth John 4:23-24