David Ernest Hornell was born on 26 January 1910. He attended John English School, then Mimico High School, graduating with honours and obtaining the Fred Werden scholarship – awarded in memory of a Mimico resident killed in the World War I. He also attended Toronto’s Western Technical School.

Hornell was an athletic young man; he enjoyed rugby, tennis and track and field. His combination of excellence in sports and academics resulted in a university scholarship offer. Times were tough, however – the Great Depression was just beginning – so Hornell took a job with the Goodyear Tire and Rubber Company. Hornell also taught Sunday school at Wesley United Church.

Hornell married Genevieve Noecker, a music teacher, in late 1943.