When Basilio Contreras was born on 9 May 1897, in Catamarca, Argentina, his father, Eugenio Contreras, was 27 and his mother, Sebastiana Silvera, was 27. He had at least 1 daughter with Lidia Mirabal.
Some characteristic forenames: Spanish Jose, Juan, Jesus, Manuel, Carlos, Luis, Miguel, Francisco, Guadalupe, Roberto, Mario, Pedro. Portuguese Duarte, Ligia, Paulo, Wenceslao.
Spanish: habitational name from Conteraras, a place in the province of Burgos, named from Late Latin contraria ‘surrounding area, region’ (from the preposition contra ‘opposite, against, hard by’).