Marilyn Manson's ex-girlfriend Rose McGowan fears she'll never be as smart as her over-achieving sisters.

The CHARMED star, who once wore nothing but a see-through fishnet dress, high heels and a G-string to an awards show, insists her acting career means nothing when she compares herself to sisters DAISY and AVA.

She explains, "My sister Daisy is an art history teacher who's going to be the youngest person to have tenure at Colorado College.

"My other sister, Ava, is a scientist - she's just been recruited by Boeing."