Getting so big!

Jessica Simpson, 35, took to Instagram yesterday remind us once again how adorable her kids are — and we can't believe how much Ace Knute has grown!

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Too tall for the jungle gym #2yroldproblems #aceknute

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RELATED: Jessica Simpson Takes an Adorable Selfie with Maxwell on Instagram

Ace and big sister Maxwell, 3, are no strangers to the camera, regularly posing for their mama. It's obvious the toddler clearly inherited his mom's love of fashion — check out his mini fedora!

See more of the cutest celebrity kids here!