The second of four children, Belaúnde was born in Lima into an aristocratic family of Spanish forebears: his father, Rafael Belaúnde Diez Canseco (1886–1972), a professor, served as Prime Minister under José Bustamante y Rivero; his paternal grandfather, Mariano Andrés Belaunde was a Finance Minister; and one of his great-grandfathers, Pedro Diez Canseco, was also President of the Republic.