Madrid, Spain, 29th July 1969, Prince Juan Carlos de Bourbon of Spain is pictured with his wife, Princess Sofia of Greece, with their children L-R: Princess Cristina, Prince Felipe and Princess Elena in their home, the Zarzuela Palace [Getty Images]

Madrid, Spain, 29th July 1969, Prince Juan Carlos de Bourbon of Spain is pictured with his wife, Princess Sofia of Greece, with their children L-R: Princess Cristina, Prince Felipe and Princess Elena in their home, the Zarzuela Palace (Photo by Paul Popper/Popperfoto via Getty Images/Getty Images) — see more

Madrid, Spain, 29th July 1969, Prince Juan Carlos de Bourbon of Spain is pictured with his wife, Princess Sofia of Greece, with their children L-R: Princess Cristina, Prince Felipe and Princess Elena in their home, the Zarzuela Palace (Photo by Paul Popper/Popperfoto via Getty Images/Getty Images)