Walt Disney World now requires that children under the age of 14 must be accompanied by someone who is at least 14 years of age. The new policy went into effect on March 23 and applies to Animal Kingdom, Magic Kingdom, Epcot, Hollywood Studios, DisneyQuest, Blizzard Beach, and Typhoon Lagoon. Previously only those under the age of 7 had to be accompanied by someone at least 14 years old.
http://land.allears.net/blogs/kristin-ford/2013/03/_in_less_than_two.html