A new experiment has found that parents can't tell when their children are lying.
In the study, parents watched videos of their children answering questions on whether they looked at the answers, for a test they had just taken.
It found they could only tell if their children were lying half the time, so the kids were able to trick their parents into believing them.
The researchers think parents distort certain information about their loved ones, to support their view or belief in them.
Other research has found that children who lie can become more successful adults, because they have stronger cognitive abilities.