Family of Cronus
Cronus was a child of Uranus, the god of the sky, and his wife Rhea. According to Apollodorus , Cronus was the youngest and weakest, but smartest of the Titans.
Cronus was married to his own sister Rhea and, after throwing their father to the depths of the underworld, they took the throne of the world together as King and Queen.
The Birth of the Olympian Gods
Cronus and Rhea gave birth to six of the fourteen Olympian Gods, including Zeus, the King of the Gods, Hera, the goddess of marriage and wife of Zeus, Poseidon, the god of the seas, Hestia, the goddess of the hearth, Demeter, the goddess of agriculture and Hades, the Greek god of the Underworld.
The Downfall of Cronus
Just like his father Uranus, Cronus was a very envious deity and swallowed his children because he had been told that one of his descendants would dethrone him one day.
So, when Rhea was expecting her last child Zeus, her parents advised her to cross the seas and reach the island of Crete. Rhea obeyed and gave birth to Zeus inside a cave in Lyctos, Crete, far away from her husband. She then left her child to be raised by Gaea and the Nymphs and quickly returned to Mount Olympus all alone. There, she deceived Cronus by giving him a stone, wrapped in swaddling clothes, to swallow.
This way, Zeus escaped from the threat and remained in Crete until he was mature enough to fight against his father and claim the Kingdom of the World.
The Library of Apollodorus (born c. 180 BCE)