"Research ... showed that young children cannot understand the potential effects of revealing their personal information; neither can they distinguish between substantive material on websites and the advertisements surrounding it. While some parents tried to monitor their children's use of the Internet services, many of them failed due to lack of time, computer skills, or awareness of risk. ... 'a Los Angeles television station reported that it obtained a detailed computer printout of the ages and addresses of 5,500 children living in Pasadena simply by sending $277 to a Chicago database firm.'"[2]
[1] http://www.msnbc.msn.com/id/14718350 [2] http://epic.org/privacy/kids/#introduction