Sir Stanley Unwin (1884-1968), noted British publisher, was dining with a foreign publisher who offered him a cigarette. Sir Stanley rejected the offer, saying "I tried it once but didn't like it." At the end of the meal the foreign publisher suggested a brandy. Sir Stanley refused: "I tried it once but didn't like it." Next day, Sir Stanley introduced the foreign publisher to his son. The foreign publisher quipped "Your only son, I take it?"
(In fairness, I should point out that I have also seen this posted as a joke and that I have been unable to track down any further reference to the incident beyond the above entry in a book of collected wit and wisdom of various persons).