Reese Witherspoon's eldest son, Deacon Phillippe, turned 13 on Oct. 23, and the proud mum marked the special occasion with a sweet Instagram message. On Sunday, Reese posted a shot from her and Deacon's Summer hiking trip in British Columbia, writing, "#HBD to my sweet boy Deacon on this special day! 🎉🎂You are such a ray of sunshine in all of our lives. ☀️Your sense of humor, kindness, and joy never cease to amaze me!!! I ❤️ you! #13." In addition to Reese's fun Instagram photos, we've also witnessed her close bond with Deacon grow throughout the years. Over the Summer, she shared a snap from his elementary school graduation and captioned it, "Off to Jr High! Yay, Deacon! #proudmom."