The people of Motunui are uniquely futanari.

Moana Waialiki sat back on the sandy shore of her home island Motunui. She enjoyed the feel of the sand against her naked skin, feeling the ocean coming up to her toes. She was always attracted to the prospect of the ocean, despite her parents (especially her mother Chief Tui) doing everything they can to keep her on the island. She always wanted to go out and explore the vast Atlantic Ocean. She never could remember why exactly, whether it was to find new islands, see the edge of the world or to actually see real men and women.

The people of Motunui were unique to the rest of the world, as they were all a part of a unique gender called the futanari. Futanari are unique in that they are just like human women, but they had penises instead of clits. They could impregnant and be impregnated. All children of futanari are futanari, no matter what the other parent was, so it only took a generation or two before the entire island's population almost exclusively futanari. How it started no one really remembers. Some say the people were blessed by a native Kaitiaki, others think they were cursed by the Taniwha.

The only human Moana has ever met that wasn't a futanari was her Grandmother Tala, so Moana could not help but be curious.