I over simplified my answer, but it's still remains the same. The wickedness is from miscegenation. Specifically, between species. Man thinking he could be God. The knowledge came from the fallen angels. The nephilim were the product of angels breeding with humans. Let's break it down a bit more. Bloodlines are so very important in the bible. RH+ blood has markers in the blood from the rhesus monkey. This is important to remember. RH- blood has no animal markers. This makes sense because God made man separate from animals. This is the blonde haired blue eyed Aryan blood of the original humans. I postulate that the RH+ blood was from the early miscegenation of man and animal spoken of in the book of Enoch. This would explain niggers. Now to get back to the verse you quoted, that is due, in part, to the nephilim blood. According to Enoch, God cursed the children of the fallen angels (nephilim) to carry the sins of their parents in their blood. They are inherently evil and no good can come from them. The fallen angels were punished by being made to watch their children kill one another. The flood was sent and Noah saved specifically because Noah was the only living person left with pure DNA, not because he was a righteous man. So yes, it ALL comes down to who slept with who. If you'd like to go further down this rabbit hole then you'll come to understand that all of our modern tech came from the pre-flood civilizations who received it from the fallen angels.