A Canadian study says children who lie are really just developing their intelligence.
The study, done by the the Institute of Child Study at Toronto University, surveyed 1,200 children aged two to 17.
The children's honesty was tested by telling them not to peek at a toy placed behind their backs while leaving the room.
Their reactions were then monitored by video and the children were asked if they had turned around. Their responses were checked against the recording.
Only a fifth of 2-year-olds were able to lie. But by age 4, 90 percent were capable of lying. The rate peaked at age 12.
The director of the institute, Dr. Kang Lee, said parent's should not be afraid that their children are going to turn out pathological liars if they catch them in a lie.
Kang called it a "developmental milestone."