Hamilton was adopted at six weeks of age by two university professors, joining an older born-to daughter. Later his family adopted another son.
He stopped growing when he was three or four years old, and spent four or five years going the rounds of doctors and hospitals in an attempt to diagnose his condition. Several diagnoses were made, including cystic fibrosis and Schwachman-Diamond syndrome, but none was correct, and he was put on a number of different diets to correct the problem, which was an inability of his body to absorb nutrients. When he was nine, however, the problem simply went away and he began to grow again, although he never grew to be more than 5' 3½" (1.61m) tall and 108 lb. (49kg). His mother died in 1977.
He began skating when he was nine and became a champion at 22, winning 16 championships in a row. He won the Olympic gold medal in 1984 and the World Championships in 1981-84. He has been elected to the Figure Skating Hall of Fame and received the Jacques Favart Award, the highest award of the International Skating Union. Since 1984 he has been a professional entertaining skater and is very involved in medical charities for children. In 1997 he was diagnosed with testicular cancer and is undergoing chemotherapy.
As a boy he once asked his mother who his birth parents might be, and her hurt response has put him off making any further enquiries.