La Genesi

When men began to multiply on earth and daughters were born to them, the sons of God saw how beautiful the daughters of man were, and so they took for their wives as many of them as they chose. Then the Lord said: "My spirit shall not remain in man forever, since he is but flesh. His days shall comprise one hundred and twenty years." At that time the Nephilim appeared on earth (as well as later), after the sons of God had intercourse with the daughters of man, who bore them sons. They were the heroes of old, the men of renown. (Genesis 6:1-4)