they have these weird caves. a rock can become a moron, so gorons that comes from the same cave are considered relatives. the gorons are a male only tribe, though there is an instance of a female fin the OoT manga
If you have seen Thor love and thunder my friend had a theory that they just reproduce like the cave thing Korg was talking about ¯\_(ツ)_/¯ but it still is like rlly weird