While the '90s were the decade of the boy/girl bands, the aughts belonged to solo superstars. Britney. Christina. Usher. Avril. Eminem. Alicia.
Born just four years apart into a devout Christian family, as teens they entered an industry that cast them in opposing roles: Jessica was all blonde waves and popular-girl aesthetic; Ashlee, the little sister stepping out of a shadow with smudged eyeliner and leather cuffs.
Now, two decades on, the sisters' days of high-flying world tours and two-tone dye jobs have given way to parenthood, memoir writing and a billion-dollar fashion empire.
Ashlee Simpson: rebel sister to (soon to be) mother of three.
An actor in her teens (credits include wholesome family drama 7th Heaven), Ashlee later established a music career on the back of her appearances in Newlyweds, the hugely popular reality show centred around her sister's marriage to Nick Lachay.
A spinoff series, The Ashlee Simpson Show, charted the recording of her first album, the pop-rock Autobiography, which sold more than 5 million copies worldwide.
Then came that infamous lip-synch mishap on Saturday Night Live in 2004, in which she mimed the lyrics to the wrong song. It was a 'gotcha' moment from which Ashlee's music career never quite recovered.