According to some behavioural experts, babies can begin constructing simple lies as early as 6 months!
Infants quickly learnt that using tactics such as fake crying and pretend laughing could win them attention. By eight months, more difficult deceptions became apparent, such as concealing forbidden activities or trying to distract parents’ attention.
Originally it was thought that children didn’t begin lying until around the age of four. Obviously, the researchers didn’t have any kids of their own or they would have known it can start a long time before that!