They are concerned with pleasing the parent, and may fear the punishment for admitting a mistake or misdeed.
After all, you're trying to woo a special girl, apologize for a misdeed, or express your love.
Selfish: Lying to protect the self at the expense of another, and/or to conceal a misdeed.
1 "He who has the love of a good woman Is ashamed of every misdeed."
In the case of demerit there is a direct antipathy to the feelings of the misdoer, but the chief sentiment excited is sympathy with those injured by the misdeed.