Of course, The Real Housewives of Beverly Hills mom couldn't help but mark the momentous occasion with the most touching Instagram post. "21 years ago today this angel came into the world. @alexiaumansky you are kind, compassionate, smart, funny, thoughtful, beautiful inside and out," Kyle wrote in the caption to an Instagram post featuring a photo of baby Alexia and her dad, Mauricio Umansky. "On your birthday I always think of when you were 5 years old and you told me that you were in heaven and saw me and chose me to be your Mom. Thank you for choosing me and for making us proud every day. I love you."
Since it was Father's Day, Kyle also took a moment to thank the man who helped bring Alexia into this world and raise her to become the lovely young woman she is today: her husband, Mauricio. "And happy Father's Day to the King of our house @mumansky18," Kyle wrote. "I love you so much and am so grateful our girls have you as their Daddy. You love them with all your heart and soul. The love you have for them is my favorite thing about you. Happy Father's Day."
Kyle celebrated Alexia's return home from college for the summer in May. “It’s hard having her away, she’s such a home girl,” she told PEOPLE last December. “When she comes home to visit, which is often, she cries every time she leaves. I cry… it’s hard.”
But obviously, there's no distance that will ever break this mother-daughter bond.
Alexia isn't the only one of Kyle's daughters who's growing up too fast these days. Watch the RHOBH mom discuss daughter Sophia Umansky's next chapter, below.