COPENHAGEN, DENMARK - APRIL 16:  Crown Prince Frederik, and Crown Princess Mary of Denmark, with their children Prince Vincent, Princess Josephine;Princess Isabella and Prince Christian attend Queen Margrethe of Denmark's 73rd Birthday celebrations, on the Balcony of Amalienborg Palace, at Amalienborg Royal Palace on April 16, 2013 in Copenhagen, Denmark.  (Photo by Julian Parker/UK Press via Getty Images)