Last week I overheard a couple of sentences from an interesting conversation between my seven-year-old son and his girlfriend, one year his junior. They play together almost every afternoon, and are indeed very close to each other. He said: “My dad is very bright.” She said: “My dad is very bright, too.” I had no idea what had prompted this, but I knew that both of them spoke without a trace of boasting. He said: “But my dad is serious, and your dad is quite silly.” After a short pause he added: “When he is talking to us, you know.” There followed another pause. “Yes,” she conceded flatly, “my dad is serious only when he is talking to my mom.” And they continued copying Japanese characters from a large poster in the hall, next door to the bathroom, where I could hardly contain an outburst of laughter. There was no doubt that they had stumbled upon something, as her parents, later that evening, received my rendition of this brief exchange with a couple of timid giggles, and then changed the subject.