Aww — how cute!

Teen Mom 2 star Chelsea Houska's daughter is all grown up! The reality star posted an Instagram pic showing off her adorable five-year-old, Aubree!

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Tball!

A post shared by Chelsea DeBoer (@chelseahouska) on

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The 23-year-old young mom showed her support for her not-so-tiny tot when she posted a picture of the two at the little slugger's tee-ball game! We can't believe how grown up and beautiful Aubree is. Chelsea must be proud!

And she's not the only one who grew up before our very eyes! Click through the gallery to see ALL the Teen Mom kids then and now!