First of all Truthwalker Thanks for your posts. I have always been intriged by the nephilim and was very happy to find someone who sort of had the same thoughts about them.
For prisonchaplain the following to think about...
The designation "sons of God" is used four other times in the Old Testament, each time referring to angels. One example is Daniel 3:25, where king Nebuchadnezzar looks into the fiery furnace and sees four men, "and the form of the fourth is like the son of God." The translation is different and clearer in our modern versions, "like a son of the gods." Since Jesus had not yet become the "only begotten son" of God, this "son" would have had to be angelic.
Another example is Job 38:7 which says the sons of God shouted for joy when God laid the foundations of the Earth. Angels are the only entities that fit this designation since man had not been created at that time!
In Job 1:6 and Job 2:1 the "sons of God" came to present themselves before the Lord in Heaven. Among the sons of God is Satan--a further implication that the "sons of God" must have been angels.
Since the designation "sons of God" is consistently used in the Old Testament for angels, it is logical to conclude that the term in Genesis 6:2 also refers to angels.