Andromeda was the eldest child of Attuma (one of Namor the Sub-Mariner's arch-rivals) and Lady Gelva. Andromeda was raised as a traditional Atlantean warrior.
Andromeda is an Atlantean, a member of the water-dwelling race native to the undersea kingdom of Atlantis. Like most Atlanteans, Andromeda worships the ocean god Poseidon, also known as Neptune. Poseidon is a member of the pantheon from Greco-Roman classical religion. His worshippers are technically Greco-Roman classical religionists, although their worship tends to be dedicated to him with little focus on his fellow Greco-Roman deities.