Sons of God and Daughters of man?

The "riddle" of who these individuals are is quite perplexing and different authors offer different support and objections to each proposal. There are basically four possibilities.

ONE: The sons of God are identified as the descendant of Seth and the daughter of man are identified as the descendant of Cain.

Support: a) It fits the surrounding context with respect to the previous chapters genealogies of each of those lines of descent. b) there are a couple of direct parallels i.e. the sons of God "took wives" parallels Lamech "taking two wives."

Argument against: For this to be possible then we have to take the meaning of "man" is 6.1 as different than in 6.2

Response: 2 Samuel 7 uses the word "house" to mean four different things; temple, palace, dynasty, and status.

TWO: The sons of God are identified as ancient dynastic rulers and the daughters of man are identified as their royal harems.

Support: there is some sources outside the Bible that does use the phrase sons of god to identify ancient rulers.

Argument against: a) sons of god has not been used up to this point in Scripture for this particular identification b) why then is the judgment against all of mankind? This is possible since 70,000 because David took a census. [2 Samuel 24]

THREE: The sons of God are identified as Angels and the daughters of man as human female.

Support: a) In other places in Scripture Angels are referred to as "sons of God" [Job 1, 2, 38] b) Jude 6 and 7 seem to support this interpretation.

Arguments against: Jude 6 and 7 may refer to similar sexually based sin, one of Sodom and Gomorrah and the other of angelic unnatural lust of angels. However, if the intent of Jude 6 and 7 is to provide two examples of divine judgement upon sin period one angelic and the other human than Jude has no import upon Genesis 6.

FOUR: the sons of God are identified as aliens...that's just one I threw in for those of you who are all confused and need a laugh.

POINT: The Biblical text introduces us to the sons of God and the daughters of man without any kind of roll call where we might know of whom God is referring to specifically but is this the point of the text? It seems that the judgment of God takes front and center albeit delayed, as evidence of His grace. It also appears that the reason for the judgement is upon illicit marital unions between God's children and others...read: believers and unbelievers, which has other Biblical support.

It is a wonderful exercise to think critically upon such issues but simply because we, at the end of the day, cannot say definitively one way or the other does not mean that we aren't able to decipher what God wants us to know about Himself. Here we need to focus upon the differentiation of flesh and spirit and the grace of God.