Born in Ottawa, Ontario, Heggtveit was raised in New Edinburgh, a northeast suburb. She was encouraged into alpine skiing by her father, Halvor Heggtveit, a Canadian cross-country champion who qualified for the Winter Olympics in 1932, but did not compete. His parents had emigrated from Norway to North Dakota. She learned to ski at Camp Fortune ski area in the nearby Gatineau Hills of Quebec, northwest of Ottawa, and was a student at Lisgar Collegiate Institute in Ottawa. Heggtveit was a ski racing prodigy, invited at age seven to serve as a forerunner to a downhill race at Lake Placid in 1946.