Today is Reese Witherspoon's daughter's 16th birthday!

To celebrate, the 39-year-old mom-of-three posted an incredibly heartfelt message to Ava on Instagram, calling her "kind, compassionate, brilliant, artistic" and an "all-around wonderful daughter who makes me a better person everyday."

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Upon first glance at the photo, it's easy to mistake the 16-year-old for Reese – after all, she's a spitting image of her mother. They definitely look more like sisters than mother and daughter!

Click through the gallery to see more celebrity parents who look like they could be their kids' siblings.