Ronaldo de Assis Moreira was born on 21 March 1980 in the city of Porto Alegre, the state capital of Rio Grande do Sul, Brazil. His mother, Miguelina Elói Assis dos Santos, was a salesperson who studied to become a nurse. His father, João de Assis Moreira, was a shipyard worker and footballer for local club Esporte Clube Cruzeiro (not to be confused with the larger Cruzeiro Esporte Clube). After Ronaldo's older brother Roberto signed with Grêmio, the family moved to a home in the more affluent Guarujá section of Porto Alegre, which was a gift from Grêmio to convince Roberto to stay at the club. Still, Roberto's career was ultimately cut short by injury. It was in their new home where his father hit his head and drowned in the swimming pool when Ronaldo was eight. Today, Roberto acts as his manager, while his sister Deisi works as his press coordinator.