SYDNEY, AUSTRALIA - OCTOBER 26: Prince Frederik of Denmark and Princess Mary of Denmark walk through the Australian Twin Registry (ATR) at the Children's Hospital on October 26, 2013 in Sydney, Australia. Prince Frederik and Princess Mary will visit Sydney for five days and will attend events to celebrate the 40th anniversary of the Sydney Opera House and the Danish architect who designed the landmark, Jorn Utzen. (Photo by Rob Griffith-Pool/Getty Images)
