Poseidon's family. His dad is Cronus and his mother is Rhea. His brothers are Zeus and Hades. His sisters are Hera, Hesita, Demeter and Aphrodite. His grandparents are Gaia and Uranus. One of his sons were Theseus. He even had a child with Medusa, before she was the Medusa we know her as. He had many wife's including his sister Demeter. One of his sons were Triton the god of messaging in the sea. He was the father of all cyclopes and one of the more famous one's was Polyphemus. Amphitrite was Poseidon's wife and she was a sea goddess and ruled the sea with him. Poseidon has a huge family like all the Greek Gods.