Genesis 6:1-4

When men began to multiply on the surface of the ground, and daughters were born to them, God’s sons saw that men’s daughters were beautiful, and they took any that they wanted for themselves as wives. The LORD said, “My Spirit will not strive with man forever, because he also is flesh; so his days will be one hundred and twenty years.” The Nephilim were in the earth in those days, and also after that, when God’s sons came in to men’s daughters and had children with them. Those were the mighty men who were of old, men of renown.