We know Princess Serenity's mother is Selene but her traditional lover, Endymion is given to her daughter, Princess Serenity as a love interest instead of her.
Selene and Endymin went on to have fifty daughters, the Menae, but Selene has another, lesser known daughter: Pandia.
Pandia is the goddess of the full moon who's father is Zeus himself. It makes sense to me that Sailor Moon is Pandia.
Christy Leigh Stewart.com