Galatians 3:26 For ye are all the children of God by faith in Christ Jesus.
The sons of Seth were the sons of God. The children of Cain were the children of men.
When they had children together they had a stronger gene pool. That made them stand out above the generations of brothers and sisters gradual weakening gene pool.
Angels don't procreate, Luke 20:35,36, and we won't either if we go to heaven.
Proverbs 8 is about Solomon's prize possession, wisdom.