Unlike most yōkai which are born as monsters, rokurokubi and their close relatives nukekubi are former humans—transformed by a curse resulting from some evil or misdeed. Perhaps they sinned against the gods or nature, or perhaps they were unfaithful to their husbands. In many cases, their husbands or fathers actually committed the sin. By some cruel twist of fate the men escape punishment and the women receive the curse instead. In any case, the rokurokubi curse only affects women.