I bet you thought you would get a deep theological and exegetical argument for the godly line of Seth view on Genesis 6:1-4 or something, didn't you? :) Wrong, but I can do you one better! According to the 18th century collations of medieval Hebrew manuscripts by Benjamin Kennicott, one scribe apparently made a fun scribal mistake in Genesis 6:11 that adds an extra occurrence of the phrase בני האלהים "the sons of God" to the Bible! Instead of the לפני האלהים lifney ha'elohim "before God" of all the other manuscripts and versions, MS 600 reads לבני האלהים livney ha'elohim "by the sons of God," making the verse read "And the earth was corrupted by the sons of God, and the earth was filled with violence." Since there is only one letter difference פ/ב "f/v" and their sounds can be easily confused, I think the scribe probably made an accidental mistake as he read the text to himself and then wrote what he thought he had said, probably under the influence of the preceding occurrences at the beginning of the chapter and the influence of the somewhat unusual articular occurrence of האלהים lit. "the God," which occurs in the other occurrences of the "sons of God" in Genesis 6. But whether it was an accidental or intentional change, it is an interesting variant that artificially creates an intertextual allusion back a few verses earlier to the sons of God of Genesis 6:1-4. It doesn't solve the sons of God debate, but it does make for a fun variant!