Mary Sharon Chalmers was born in Fredericton, New Brunswick on 19 April 1936, to Eloise and George Everett Chalmers. Eloise had been a nurse prior to marrying Everett Chalmers, a prominent local physician. Sharon was raised in a family and time when appearances and family ties were extremely important; although her mother knew her father was unfaithful to her, she refused to leave him. Sharon had a younger brother, Peter Chalmers, who was born 19 October 1937. When Sharon was younger her parents often took her and her brother on trips, including to Banff, Vancouver, and through the U.S. She had exposure to large scale American musical theatre as the family traveled to New York, where she saw popular musicals such as Annie Get Your Gun, South Pacific, and Oklahoma!