Why is it so easy to understand children

Adult people are much harder to understand than children, because with age the face loses muscle tone.
With age is associated with the speed of some gestures and their obviousness to others. For example, if a five-year-old child decides to deceive you, he will almost certainly immediately cover his mouth with one or both hands.

This kid is clearly cheating.
Such a gesture should alert the parents. However, the habit of covering up the mouth during deception lasts throughout a person’s life, only the speed at which the gesture is performed changes. When a teenager cheats, he covers his mouth in the same way as a five-year-old kid, but his gesture is not so obvious. Teenagers often rub their mouth with their fingers.
The teenager is telling lies
In the adult state, the habit of covering the mouth is realized even faster. When an adult is deceiving, it seems that his brain gives an order to his hands to cover his mouth in order to block false words. Similarly, an adult behaved in childhood and in adolescence. But at the last minute the hand stops halfway, and the person instead of the mouth touches the nose. Touching the nose is an adult version of a child’s attempt to cover the mouth.
Clinton answers questions about Monica Lewinsky before a grand jury
In this example, we are convinced that with age, people's gestures become more imperceptible and less obvious. That is why it is more difficult to interpret the gestures of a fifty-year-old man than the gestures of a five-year-old girl.