I don't think it's incongruous for the characters involved. In Peter's Room Nick asks Rowan to check if the cows are kneeling at midnight, and Rowan funks it, and Nick knows she would have too, and Peter thinks that the farthings are bewitched. So I think the supernatural is something that they are happy to believe, or at least to pretend to themselves that they do, and they have the slightly arch way of family jokes etc, so that they wouldn't question Patrick's beliefs.