Genesis 6:2 WEB

¹  It happened, when men began to multiply on the surface of the ground, and daughters were born to them,

²  that God's sons saw that men's daughters were beautiful, and they took for themselves wives of all that they chose.

³  Yahweh said, 'My Spirit will not strive with man forever, because he also is flesh; yet will his days be one hundred twenty years.'

⁴  The Nephilim were in the earth in those days, and also after that, when God's sons came to men's daughters. They bore children to them: the same were the mighty men who were of old, men of renown.