US President Barack Obama and first lady Michelle Obama don't let their daughters on Facebook. The social network may have over 800 million monthly active users, but neither Sasha Obama nor Malia Obama are included in that huge number.

The new information comes straight from the source: both parents sat down for an interview with People magazine for their year-end double issue. Their girls are not allowed on the world's largest social network for a very simple reason: "why would we want to have a whole bunch of people who we don't know knowing our business? That doesn't make much sense."

It apparently wasn't a hard decision to enforce at the White House, though the First Lady pointed out that Malia is 13-years-old and Sasha is only 10-years-old right now. That's when the US President laughed and added "We'll see how they feel in four years."

The age question is very important. Technically, only Malia is allowed to have an account on Facebook. The Children's Online Privacy Protection Act (COPPA) mandates that websites that collect information about users aren't allowed to sign on anyone under the age of 13. As a result, Facebook's Statement of Rights and Responsibilities require users of the social network to be at least 13 years old (and even older, in some jurisdictions).

Millions of preteens use the service anyway: some get permission from their parents to create an account while others lie about their age to get past sign-up restrictions. Earlier this year, it was estimated that 7.5 million Facebook users are below the minimum age. To make matters even more worrying, more than 5 million were 10-years-old or younger. For its part, Facebook says it's a very tough problem to solve.

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