Kitson was born in Brookline, Massachusetts, to Cyrus W. and Anna H. Ruggles. As a young child she displayed artistic talent, but when her mother attempted to enroll her in the School of the Museum of Fine Arts, Boston, she was informed that she was too young to be admitted. Her mother then approached other schools, which gave her the same advice. One of the school directors, however, suggested that she find a tutor for her and pointed her in the direction of a rising star, Henry Hudson Kitson.