Again you can speculate and I can speculate but it is not biblical.
Find the scriptures that the sons of God presented idols, and they were specifically the targets of the flood. What the scriptures actually says is….Now the earth was corrupt in the sight of God, and the earth was filled with violence. And God looked on the earth, and behold, it was corrupt; for all flesh had corrupted their way upon the earth. Then God said to Noah, “The end of all flesh has come before Me; for the earth is filled with violence because of them; and behold, I am about to destroy them with the earth. Genesis 6:11-13 No mention of the sons of God.
One of things I want you to find in the scriptures is that the sons of God impregnating these women was a bad thing. Many assume it was a bad thing, but was it? And it referrers to marriages. How long did they stay with these women? Did they raise these children? Was the event to produce men to kill these Giants? Again just speculation. If you cannot produce the scripture saying it was a bad thing, it is speculation.
Genesis 6:1-4
Now it came about, when men began to multiply on the face of the land, and daughters were born to them, that the sons of God saw that the daughters of men were beautiful; and they took wives for themselves, whomever they chose. Then the Lord said, “My Spirit shall not strive with man forever, because he also is flesh; nevertheless his days shall be one hundred and twenty years” The Nephilim were on the earth in those days, and also afterward, when the sons of God came in to the daughters of men, and they bore children to them. Those were the mighty men who were of old, men of renown.