He was born on a farm in Bromptonville, Quebec in the Eastern Townships and was educated in Montreal at both English and French high schools.
His father, Joseph-Omer Asselin, was chairman of Montreal City Council's powerful executive committee.
After graduating from high school, Asselin attended St. Mary's College in Halifax, Nova Scotia, and then returned to his home town to run the family's dairy farm.
Asselin stepped in as the new candidate, and defeated incumbent Social Credit MP André Bernier by 350 votes.
His defeat came six months short of the minimum period of service required at the time to qualify for a parliamentary pension.
Warren Allmand, a former Liberal Canadian cabinet minister, later said of Asselin: "He wasn't egotistical.