I'm not sure that works in law. A 13-year-old could click "consent" and not make a contract with FB.
In that sense, it shall be treated as if there hasn't been a contract at all. The process is purposefully designed to get a signed contract as fast as possible. The technology to make proper ID (Age) verification is available, but my understanding is, that it is not used by facebook and its partners.
I mixed two points here. Contracts that contradict the law and my wish for better regulations.