In the entire Old Testament, the word "bene elohim" meant one thing and one thing only: Angels or, more accurately, spiritual beings.
I won't go into too much detail because my experience is that once people want to believe that the Sons of God are humans (be it the sons of Seth baloney or powerful rulers crap), they cannot be dissuaded.
That said, consider this:
Job 1:6
Now there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them.Job 2:1
Again there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them to present himself before the LORD.Job 38:7
When the morning stars sang together, and all the sons of God shouted for joy?
In addition to the Old Testament there is a massive amount of extra-Biblical literature that tells us who the Sons of God are...and they ain't human.
Proof by assertion.
Angels do not reproduce, or else the universe would be overfilled with them.