julio mario santo domingo was born on october 16, 1923 in panama city, panama, to julio mario santo domingo santo domingo and beatriz pumarejo de vengoechea, the youngest of their four children; his older siblings were beatriz alicia, cecilia, and luis felipe. his father was a banker, described as austere and disciplined, who made a fortune buying companies weakened during the great depression; his mother, from a rich and influential family, was first cousin of alfonso lópez pumarejo who was twice president of colombia. he grew up in barranquilla and later attended the exclusive gimnasio moderno in bogotá, d.c., ultimately culminating his secondary studies at the phillips academy in andover, massachusetts; he later attended university of virginia before transferring to georgetown university, but did not finish his degree.