Social media sites like Facebook and Twitter may have eroded levels of privacy by giving people a place to post every facet of their lives and the people around them. However, it's also given parents a way of doing some sneaky snooping into their children's lives.

A new study from Research Now of 4,400 parents found that six out of 10 admitted to using Facebook to "spy" on their kids without their children knowing about it. Just under half also admitted to signing in to their children's account to keep tabs on them. Mothers are also more likely to check on their kids through their Facebook page than fathers.

All of this invasion of personal privacy may not have been for naught. The study also found that almost a quarter of the parents who hacked their way into their kids' Facebook pages found "abusive or explicit messages." Fourteen percent of those parents also found abusive or explicit text or voice mail message on their children's cell phones.

Parents have good reasons to be concerned about what their kids are doing or saying on sites like Facebook. The medium age of the average user is shrinking. Facebook doesn't allow children under the age of 13 to use their service, but more than half of children aged 10 to 13 were able to get an account with the help of a parent who could circumvent Facebook's policies.

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