Who is XXX's sister?
Aga Khan IV
Born Prince Karim Aga Khan, the Aga Khan IV is the eldest son of Prince Aly Khan, (1911--1960) and his first wife, Princess Tajuddawlah Aly Khan, formerly the Hon. Joan Barbara Yarde-Buller (1908--1997), the eldest daughter of the 3rd Baron Churston.