Hilary Duff’s son, Luca Cruz, has officially stepped into his teenage years. The actress took to Instagram on March 20 to celebrate his 13th birthday with a heartfelt post. Duff shared a collection of photos which captured Luca’s journey from childhood to till now. The post included solo pictures of him over the years, moments with his sisters and even a throwback from the delivery room where she lovingly embraced him. In her caption, Duff, 37, expressed her disbelief at how quickly time has passed. “Wow— is time ever a thief. I thought ten years of being a mom felt wild…yet here I am at my son’s 13th birthday,” she wrote. “I can’t go anywhere without people telling me what a nice kid Luca is. Sweet, heart facing forward with the coolest point of view. He can talk anyone under the table about soccer, players dating back to the 70s, specific games that defined history…He’s an amazing creative drawer, a beautiful writer (hopefully more of that in the future) and I *think* taking a new interest in history,” the Lizzi Mcquire alum continued. Duff further shared how much she enjoys hearing Luca talk about history, something he has recently taken a strong interest in. Since she didn’t have a “normal” schooling experience, she admitted that there were “definitely some gaps” in her knowledge. View this post on Instagram A post shared by Hilary Duff (@hilaryduff) “It’s sure cool to have the tables turned and see how much more he knows than me…Just in this one instance of course,” she added. Duff expressed how incredible it has been to watch Luca grow saying it’s “so cool to see his interest shift.” She admired his “sure-footedness” and how he is continuously learning and evolving. “My only son. I love you more than the moon and as far as all the stars in the sky,” the actress expressed. Duff then listed all the little things she loves about him, from texting and late-night kitchen conversations to driving him around. “Watching you play soccer is the best. Listening to hip-hop with you is the best (let’s gooo Kendrick and Lil Tecca). The kind of big brother you are is the best. Your smile is the best. Your humour is the best. You being fully YOU is the best. Being your mom is the BEST,” she further wrote. The Younger star ended her message with, “HAPPY 13, Angel. Forever standing by to cheer you on.” Luca was born in 2012 during Duff’s marriage to former hockey player Mike Comrie. After their divorce, she later married musician Matthew Koma in 2019. Together, the couple has three daughters – Banks, 6, Mae, 3, and Townes, who was born in May 2024.