Romero was born and grew up in Bernardo de Irigoyen, Misiones, Argentina. His two older brothers became basketball players, but due to Sergio’s smaller stature in comparison to them, Romero earned the nickname ‘chiquito’ which means little. He is married to Eliana Guercio, an Argentine model, vedette and actress. She is currently working in shows hosted by Gerardo Sofovich in Buenos Aires’s Corrientes Avenue.