Hamilton was born on August 28, 1958 in Toledo, Ohio.[4] He was adopted at the age of six weeks by Dorothy (née McIntosh), a professor, and Ernest S. Hamilton, a professor of biology,[5] and raised in Bowling Green, Ohio. He has two siblings, older sister Susan (his parents' biological daughter) and younger brother Steven (who was also adopted).[6] He attended Kenwood Elementary School. When Hamilton was two years old, he contracted a mysterious illness that caused him to stop growing. After numerous tests and several wrong diagnoses (including a diagnosis of cystic fibrosis that gave him just six months to live), the disease began to correct itself. His family physician sent him to Boston Children's Hospital to see a Dr. Shwachman. He was told the doctor had no idea what was wrong and to go home and stop the diets in order to live a normal life. Years later, it was determined that a congenital brain tumor was the root cause of his childhood illness