Kuerten was born in Florianópolis in southern Brazil. He began playing tennis when he was six, an early start to a life and career marked by family tragedy. His father, Aldo, a former amateur tennis player, died of a heart attack in 1985 while umpiring a junior tennis match in Curitiba, when Kuerten was eight years old. His older brother, Raphael, is currently his business manager. His youngest brother, Guilherme, suffered prolonged oxygen deprivation and consequently irreparable brain damage during birth, and as a result suffered from mental retardation and severe physical disability until his death in 2007. Kuerten was deeply affected by his brother's daily struggles, later donating the entire prize money from one tournament he has won every year of his professional career so far to a hometown NGO that provides assistance for people suffering from similar disabilities. He gave every trophy he won to his younger brother as a souvenir, including the three miniature replicas of the French Open men's singles trophy.