knew.

Numbers 31:17
So now, kill all the boys, and kill every woman who has had relations with a man,

Cain.

I have.

Genesis 4:25
And Adam again had relations with his wife, and she gave birth to a son and named him Seth, saying, "God has granted me another seed in place of Abel, since Cain killed him."

Genesis 3:15
And I will put enmity between you and the woman, and between your seed and her seed. He will crush your head, and you will strike his heel."

Genesis 5:29
And he named him Noah, saying, "May this one comfort us in the labor and toil of our hands caused by the ground that the LORD has cursed."

1 John 3:12
Do not be like Cain, who belonged to the evil one and murdered his brother. And why did he slay him? Because his own deeds were evil, while those of his brother were righteous.