text: is the grand duchess of luxembourg really fidel castro's niece?   no she isnt. she fled cuba with her parents due to the revolution. on the other hand u.s. representatives mario diaz-balart and lincoln diaz-balart who are anti-castro politicians from florida are related to fidel. fidel's first wife was their aunt and a member of the diaz-balart clan. fidel's son, fidelito,  is the child produced during their marriage.