From a NYMag article by Po Bronson:
The most disturbing reason children lie is that parents teach them to. According to Talwar, they learn it from us. “We don’t explicitly tell them to lie, but they see us do it. They see us tell the telemarketer, ‘I’m just a guest here.’ They see us boast and lie to smooth social relationships.”
Consider how we expect a child to act when he opens a gift he doesn’t like. We instruct him to swallow all his honest reactions and put on a polite smile. Talwar runs an experiment where children play games to win a present, but when they finally receive the present, it’s a lousy bar of soap. After giving the kids a moment to overcome the shock, a researcher asks them how they like it. About a quarter of preschoolers can lie that they like the gift—by elementary school, about half. Telling this lie makes them extremely uncomfortable, especially when pressed to offer a few reasons why they like the bar of soap. Kids who shouted with glee when they won the Peeking Game suddenly mumble quietly and fidget.
Meanwhile, the child’s parent usually cheers when the child comes up with the white lie. “Often, the parents are proud that their kids are ‘polite’—they don’t see it as lying,” Talwar remarks. She’s regularly amazed at parents’ seeming inability to recognize that white lies are still lies.
When adults are asked to keep diaries of their own lies, they admit to about one lie per every five social interactions, which works out to one per day, on average. The vast majority of these lies are white lies, lies to protect yourself or others, like telling the guy at work who brought in his wife’s muffins that they taste great or saying, “Of course this is my natural hair color.”
Encouraged to tell so many white lies and hearing so many others, children gradually get comfortable with being disingenuous. Insincerity becomes, literally, a daily occurrence. They learn that honesty only creates conflict, and dishonesty is an easy way to avoid conflict. And while they don’t confuse white-lie situations with lying to cover their misdeeds, they bring this emotional groundwork from one circumstance to the other. It becomes easier, psychologically, to lie to a parent. So if the parent says, “Where did you get these Pokémon cards? I told you, you’re not allowed to waste your allowance on Pokémon cards” this may feel to the child very much like a white-lie scenario—he can make his father feel better by telling him the cards were extras from a friend.
(via CTBlog)