‘… the jokes about a mother-in-law are scarcely delicate, but the problem of a mother-in-law is extremely delicate. A mother-in-law is subtle because she is a thing like the twilight. She is a mystical blend of two inconsistent things—law and a mother. The caricatures misrepresent her; but they arise out of a real human enigma….. The nearest statement of the problem perhaps is this: it is not that a mother-in-law must be nasty, but that she must be very nice.’
G K Chesterton, What’s Wrong with the World.