Doctors never could explain why Nino is so small, his parents say.
"They never gave us a diagnosis," his mother, Noemi Hernandez, said during an interview in the family's sparely furnished apartment in Bosa, a mostly poor district of southern Bogota.
Hernandez, 43, said Nino weighed just 3.3 pounds (1.5 kilograms) at birth and was 15 inches (38 centimeters) long.
She said doctors at the National University studied him until he was 3, then lost interest. She and her husband, a security guard, lost a daughter who was similarly small in 1992 when she was about to complete a year of life.
The couple's youngest child, 11-year-old Miguel Angel, stands 37 inches (93 centimeters) tall and has facial features similar to Nino. The other three boys are of normal height and appearance.
"I feel happy because I'm unique," Nino said in an interview Friday with The Associated Press.