You're right. It's due to a typo in the code, we'll fix this for next update as it's not a game breaking bug. You can rename them using the console:trying to rename the family members through ingame option is giving me an error (online version) latest firefox. maybe it´s me. maybe it´s (/a) god . or maybe it´s one of those thousand of blockers. but maybe you should check yourself if it´s not the code.
example:
SugarCube.State.variables.sis.name="NAME"