By InStyle Staff
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!

MORE: • Our Top 10 Favorite Party Hairstyles• 5 New Year’s Eve Makeup Ideas• Try On Christina Aguliera's Hairstyle!