Uranus was Cronos and the other titans father and Gaia was their mother. Gaia got mad at Uranus for putting his other children the Cyclopes and the Hekatonkheires into Tartarus so she offered a scythe to her sons to kill their father with but none of them wanted to except the youngest Cronos. He took the scythe and with the help of his brothers who held his father down he cut up his father into a bunch of pieces. When he castrated Uranus the blood that dripped down into the sea made sea foam and out of it Aphrodite was born. Cronos then became the king of the titans.