By InStyle Staff
Updated Dec 18, 2011 @ 3:00 pm
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Happy Birthday Christina Aguilera! We’ve watched the 31-year-old grow up from her days on The Mickey Mouse Club to being named one of Rolling Stone’s 100 Greatest Singers of All Time. Now let’s take a look back at everything the Grammy winner-UN Ambassador-mother has done in between. Check out the gallery of her transformation!