Answer
The nationalities of Sam Mendes's parents are Trinidadian and English. His father, Alfred Mendes, was a Trinidadian novelist, while his mother, Valerie Helene, was an English children's book author. Alfred Mendes, who was born in Trinidad and Tobago, was of Portuguese-Jewish descent, while Valerie Helene, originally from Oxford, England, was likely of British descent. This mixed heritage contributed to Sam Mendes' diverse cultural background and upbringing.