Galup was born in Maldonado (Uruguay), the son of Gabriel Bacigalupe Alfaro and Inés Rodríguez Sardinha. He used the surname of his stepfather José Manuel Galup, a Genoese of Catalan roots, who had served like legal representative of Aimé Bonpland. His half brother was the lieutenant colonel, Don Pedro Rafael Galup, who participated in the War of Independence.