Toddlers capable of lying at 2 years old are probably more intelligent and will succeed in life.
A Canadian study of 1,200 children aged two to 17 suggests those who are able to lie have reached an important developmental stage.
Only a fifth of two-year-olds tested in the study were able to lie.
Dr Kang tested the children's honesty by telling them not to peek at a toy placed behind their backs while leaving the room.
He then monitored their reactions by video and returned to ask if they had turned around, checking their responses against the recording.