Desmond Robert Leak was born in Adelaide on 9 January 1956, the second of three children of Doreen and Reg Leak in what was reportedly a "blue-collar Labor family". He was brought up in Condobolin from his birth until 1967, when the family moved to Beacon Hill. He attended Beacon Hill High School and Forest High School, forced to leave the former for the latter after drawing caricatures of his teachers. Remembering what Beacon Hill was like in the early 1970s, Leak described the place as "intellectually barren, culturally hostile and isolated".