We hear a great deal about the rudeness of the rising generation. I am an oldster myself and might be expected to take the oldsters' side, but in fact I have been far more impressed by the bad manners of parents to children than by those of children to parents. Who has not been the embarrassed guest at family meals where the father or mother treated their grown-up offspring with an incivility which, offered to any other young people, would simply have terminated the acquaintance? Dogmatic assertions on matters which the children understand and their elders don't, ruthless interruptions, flat contradictions, ridicule of things the young take seriously--sometimes of their religion--insulting references to their friends, all provide an easy answer to the question "Why are they always out? Why do they like every house better than their home?" Who does not prefer civility to barbarism?
If you asked any of these insufferable people--they are not all parents of course--why they behaved that way at home, they would reply, "Oh, hang it all, one comes home to relax. A chap can't be always on his best behaviour. If a man can't be himself in his own house, where can he? Of course we don't want Company Manners at home. We're a happy family. We can say anything to one another here. No one minds. We all understand."
C.S. Lewis, The Four Loves, Affection (1960)
Quaint link of the day: Emily Post's 1922 Book on Etiquette