Celebrity Celebrity Moms Reese Witherspoon Wishes Her Son a Happy 3rd Birthday with an Adorable Photo By Meghan Overdeep Meghan Overdeep Twitter Meghan Overdeep is a writer and editor based in Brooklyn who covers all things celebrity and pop culture. She worked as a News Blogger for InStyle for two years and is currently a Senior Staff Writer at Southern Living. InStyle's editorial guidelines Updated on September 28, 2015 @ 07:45AM Pin Share Tweet Email Photo: JB Lacroix/WireImage Reese Witherspoon's littlest look-alike is growing up so fast! The actress took to Instagram to wish her youngest son, Tennessee Toth, a happy third birthday, and we just can't handle the cute. "Happy Birthday Sweet boy! 3 is a magic number" the Oscar-winning mom captioned the photo of her adorable towhead posing in the sand wearing bright blue sunglasses. Not long after, Witherspoon posted a snap of the lucky tike's birthday cake, a chocolate confection topped with a fleet of miniature construction trucks that would make any young boy drool. Tennessee isn't the only member of Witherspoon's brood to celebrate a birthday recently. Two weeks ago her daughter, Ava Phillippe, turned 16 years old—an event the proud mom marked in a similar fashion, on Instagram, of course! The 15 Cutest Photos of Reese Witherspoon and Her Look-Alike Kids