Kellerman was born Sally Clare Kellerman in Long Beach, California, on June 2, 1937 to Edith Baine (née Vaughn; 1911–1998), a piano teacher, and John "Jack" Helm Kellerman (1900–1971), a Shell Oil company executive. Her mother was a native of Portland, Arkansas, while her father was originally from St. Louis, Missouri. Kellerman has an older sister, Diana Dean Kellerman; her younger sister, Victoria Vaughn (Vicky) Kellerman, died in infancy. Kellerman's mother was a Christian Scientist, and raised her daughters in this faith.