The Book of Genesis describes a time when there was an increasing wickedness on the face of the earth that provoked God to destroy them with the floods save for Noah and his family. I suspected it could be referring to fallen angels but then why would angelic sin cause God to destroy the world with the floods? After all the verse says that it is human wickedness that caused God to bring the floods.
Genesis 6:11-13
Now the earth was corrupt in God's sight, and the earth was filled with violence. And God saw the earth, and behold, it was corrupt, for all flesh had corrupted their way on the earth. And God said to Noah, “I have determined to make an end of all flesh, for the earth is filled with violence through them. Behold, I will destroy them with the earth.
Notice the verse above, it talks about the corruption of all flesh which means it was human rebellion and the angels has nothing to do with it.
But then when we look at the Book of Job , the phrase sons of God has been used to refer to a group of angels who went to present themselves to God and Satan went with them.
Job 1:6-10
Now there was a day when the sons of God came to present themselves before the LORD, and Satan also came among them. The LORD said to Satan, “From where have you come?” Satan answered the LORD and said, “From going to and fro on the earth, and from walking up and down on it.” And the LORD said to Satan, “Have you considered my servant Job, that there is none like him on the earth, a blameless and upright man, who fears God and turns away from evil?”
Does the Sons of God refer to the lineage of Seth or does it refer to angels?