QUOTE : (...) a child is led into a laboratory and asked to face one of the walls. The experimenter then explains that he is going to set up an elaborate toy a few feet behind them. After setting up the toy, the experimenter explains that he has to leave the laboratory, and asks the child not to turn around and peek at the toy. The child is secretly filmed by hidden cameras for a few minutes, and then the experimenter returns and asks them whether they peeked. Almost all 3-year-olds do, and then half of them lie about it to the experimenter. By the time the children have reached the age of 5, all of them peek and all of them lie. The results provide compelling evidence that lying starts to emerge the moment we learn to speak. Perhaps surprisingly, when adults are shown films of their children denying that they peeked at the toy, they are unable to detect whether their darling offspring are lying or telling the truth.