If the epithet “child star” someday stops being approximately equal to “flash-in-the-pan,” then we can probably thank Mary-Kate and Ashley. But even if their audience deserts them as they age or commit some Britney Spears-style gaucherie that alienates them from the masses — or, my pet theory, they are several similar-looking actresses sharing a dual role — Mary-Kate and Ashley have already shown themselves to be two businesswomen for the ages, no matter what their age.

what made the difference for mary-kate and ashley was a combination of iron-fisted control of their careers by themselves and thorne; their still squeaky-clean, girls-next-door image, also jealously guarded; and the inherent appeal of twins.