Gemma was the daughter of Laidolf and Aldara of San Massimo. The date and place of her birth have not been found.
Her husband was Guaimar IV (V) de Salerne, who she married in ABT 1027. The place has not been found. Their seven known children were Giovanni IV (?-1039), Sikelgaita (c1040-1090), Gisulf II (c1040->1089), Guy (?-?), Giovanni (?-?), Guaimar (?-?) and Gaitelgrima (?-?).