Theseus was the son of Aegeus and Aethra.
His mother, Aethra, had once been the daughter of Pittheus, King of Troezen.
His paternal ancestors were the aged King Erichthonius and the Athenians said in legend to have sprung from the earth;
His maternal ancestor was Pelops, the mightiest of all the kings of the Peloponnese.
Pelops's son, Pittheus, founded the city of Troezen. Once, he personally received King Aegeus, who had already ruled Athens for twenty years before Jason set out in search of the Golden Fleece.
At first, his father Aegeus had no son.
Therefore, Aegeus greatly feared his brother Pallas, who had fifty sons and bore hostility toward him.
Aegeus wanted to secretly remarry without his wife knowing, hoping to have a son to comfort him in his old age and inherit his throne.
He confided his thoughts to his friend Pittheus.
Fortunately, Pittheus had received an oracle stating that his daughter would have no public marriage, yet would bear a renowned son.
Thus, Pittheus resolved to secretly marry his daughter Aethra to Aegeus, despite Aegeus already having a wife.
Hmm, very Greek indeed.
Later, Aegeus married Aethra. After staying in Troezen for a few days, he returned to Athens.
He bid farewell to his newlywed wife by the sea. As they parted, he placed a sword and a pair of sandals beneath a massive rock by the shore, saying:
"If the gods bless us and grant you a son, then raise him in secret. Do not let anyone know who the child's father is. When the child has grown into an adult, strong enough to move this rock, bring him here. Let him take out the sword and sandals, then have him bring them to Athens to find me!"
After that,
Aethra indeed gave birth to a