All kids sometimes lie to their parents. The most common reason is to avoid punishment for a deliberate or accidental misdeed. Another common motive is to obtain some reward or benefit not otherwise obtainable.
There are also lies to protect a friend or sibling, lies to enhance self-esteem (bragging), lies to get out of an awkward social situation, lies to obtain privacy from an intrusive parent, and lies to test and exert power over their own lives. The list goes on.
Parents are often hurt when they discover a serious lie, and that hurt may motivate the parent to punish more severely than is justified or useful, and unwittingly motivate the child to become a more careful liar rather than discourage future lying behavior.
To be truthful when you know that doing so will get you punished asks for more bravery than most of us, let alone our children, have.
Read the full story on how to raise a truthful child at PBS.org/Parents.