When they're so young, your kids' lies are more expressions of imagination. "I went to the moon with my friends today!" As they age, fear becomes the motive for deception -- often fear of punishment if they fess up to misbehaviors or rule violations, said Lizzi J. Kampf, a clinical social worker for Children's Hospitals and Clinics of Minnesota.

The portion of the brain responsible for executive functions and logical decision-making doesn't fully develop until adulthood, she explained. That means that children can't always comprehend that cover-ups only make things worse in the end.

"That's really something that is hard for their brains to process," she said, when comparing the risk of being in trouble now or more trouble later. "They're a lot more right-now oriented."

All of which is important for parents to understand as they teach their children the value of honesty, and why the Lance Armstrong confession of cheating in cycling might be a valuable teaching moment. (I blogged on this subject a bit Thursday, but wanted to add Kampf's insights on the matter.) It is a third-party example that cover-ups don't work and that even heroes get in trouble when they lie.

"All kinds of things in the media are opportunities," she said. "(Your kids are) going to get exposed to them regardless. You can kind of start the conversation with, 'so what have you heard about this?' ... Then ask 'what do you think about what he has said and about the dishonesty?' Then it's important for you to come back with what your family believes" about truthfulness and why it is important.

When dealing with children who have trouble with honesty, Kampf said it is OK for parents to avoid trapping their children into lies, which can just make them scared and instinctively combative. If children failed to do the dishes, parents shouldn't necessarily approach them with "did you do the dishes?" Instead, Kampf said, they can say "let's talk about a plan for how you can get these dishes done."

Kampf said it is also important to distinguish between when children are lying to cover up mistakes versus when they are "oppositional" and are lying just to get a reaction from their parents.

"It has to depend a lot on the situation. Its going to have to go back to if they're lying and they've done something wrong," she said. "I think the punishment has to go back to 'what would the punishment have been for what they lied about?' And then have the conversation about how the lying hurts their relationship."