Who were the “sons of God” in Genesis 6:1-4?

Due to the sparse contextual information with this passage, biblical scholars debate the identity of the “sons of God” in Genesis 6:1-4. Another difficulty is the brevity of the passage.

The biblical phrase “sons of God” (or children of God) refers to a being created by and in relationship with God. The interpreted meaning and subsequent translation varies according to the passage context. It may refer to angels, people in a relationship with God (either in obedience or rebellion), or someone having characteristics of or doing the work of God, as in one having authority. Theologians have come up with several theories for this specific passage. Possibilities for the identity of the “sons of God” in Genesis 6 include (1) fallen angels, (2) godly descendants of Seth, (3) sons of rulers or judges, or (4) royal “heroes” or kings of old.

I have attached a chart that outlines the various theories from John Walton’s Chronological and Background Charts of the Old Testament.
Walton - OT Charts - Sons of God.pdf (143.0 KB)