Shearer was of Scottish and Irish descent. Her childhood was spent in Montreal and was one of privilege due to the success of her father's construction business. However, the marriage between her parents was unhappy. Andrew Shearer was prone to manic depression and "moved like a shadow or a ghost around the house," while her mother Edith Fisher Shearer was attractive, flamboyant, and stylish. Young Norma was interested in music, as well, but after seeing a vaudeville show for her ninth birthday, announced her intention to become an actress. Edith offered support, but as Shearer entered adolescence, became secretly fearful that her daughter's physical flaws would jeopardize her chances. Shearer herself "had no illusions about the image I saw in the mirror." She acknowledged her "dumpy figure, with shoulders too broad, legs too sturdy, hands too blunt", and was also acutely aware of her small eyes that appeared crossed due to a cast in her right eye. By her own admission, though, she was "ferociously ambitious, even as a young girl" and planned to overcome her deficiencies through careful camouflage, sheer determination, and charm.