As the two celebrate their 40th birthday, WWD is taking a look back at their hair over the last two decades.

Mary-Kate and Ashley Olsen’s Hair Evolution Ashley Olsen and Mary-Kate Olsen attend the Metropolitan Museum of Art’s annual Costume Institute gala in 2005. Mary-Kate and Ashley Olsen’s Hair Evolution Mary-Kate Olsen (L) and Ashley Olsen front row at [1926 chars]

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