Born in El Fuerte, Sinaloa, Mexico, on 29 April 1930, Sergio Danilo Elizondo Domínguez was the ninth son. His mother died when Elizondo was five, and he lived unhappily with his father and stepmother until his father's death six years later, after which he lived with various relatives.

His father, Cristino Elizondo, was a teacher and school principal who interrupted his career to fight in the Mexican Revolution. According to Elizondo, in an unpublished 1986 interview, his father was "la otra cara de Artemio Cruz," that is, the opposite of Artemio Cruz, the selfish bourgeois protagonist of Carlos Fuente's novel La muerte de Artemio Cruz (1962), who turned his back on the people after he fought for their ideals. Elizondo was not one of his father's favorite sons, nor was he his mother's favorite either: "mimadre estaba hasta el copete de cabroncitos, de machos; cuando nací yo, aparentemente, ella...