At what age did your kiddos lie to you? I just realized my DS was lying to me a few weeks ago (20 months old). I would ask him if he pooped and he'd say 'NO' without looking guilty or changing his behavior in the slightest. He does the same thing when I saw him hide something (he didn't notice I was watching) then asked him if he hid those rocks behind the tree (not punishable by any means, just asking to keep interacting with him).
How in the world did he learn this?! He's not in day care and he's not around it much, not enough to pick up on anyway I'd think?!?! What have your experiences been?
