Kailyn Lowry Celebrates 'Brilliant, Funny' Son Isaac on His 13th Birthday: 'Such a Milestone'

Kailyn Lowry Instagram

Kailyn Lowry's oldest is celebrating a major milestone.

The former Teen Mom star's son Isaac turns 13 on Wednesday, with the mom of four sharing a heartfelt Instagram tribute to her not-so-little boy.

Alongside a video showing off Isaac's blue and white birthday bash — which the podcaster later revealed was kept to just their household as they dealt with a stomach bug going around — the 30-year-old celebrated Isaac as a "son, brother, friend."

"I don't always get super emotional on Instagram posts but this is a special occasion. Thirteen feels like such a milestone," Lowry wrote of her oldest, whom she shares with ex Jo Rivera.

"We have literally grown up together, but in some ways he's even more grown than I am. Thoughtful, brilliant, funny and at times a smartass 😆 are a few words I would use to describe Isaac," she continued.

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Lowry then celebrated Isaac for the "way he challenges social norms."

"Because he is curious and open-minded, he can form his own thoughts and opinions. Isaac also accepts people for who they are and never how they're 'supposed' to be," she shared. "More people should be like him."

She concluded the heartfelt post with her wishes for her newly-minted teen. "Isaac, I hope this year is full of happiness and adventure for you. I hope you accomplish every goal you set, I hope you learn new things and you're able to be present. I love you with my whole heart! Happy birthday! 🫶🏼."

Isaac commemorated his birthday by sharing his own Instagram post from the day with his mom, taking a moment to thank his family for the life he's had.

"Thank you, to my parents for everything. For the care, for the love, and just being in my life in the first place. I love you so much, I wouldn't be here without you," the teen wrote. "Even through the hard times, you've been there. You'll never know how happy you made me today, and everyday. So happy, I can't even express how happy I am!"

"To all of my siblings, thank you too. We may complain about each other, but at the end of the day, we're still family. I love all of you! Same goes to the rest of my family. I wouldn't have made it without any of you," he shared. "I love you all so much, and thank you for everything. We may not be able to see each other often, but you'll always have a special place in my heart. 😘✨🫶🏻."

Lowry replied to the post, writing, "😭😭😭 Isaac you do not have to thank us. We love you! you're going to have an awesome year! We are claiming it. Happy birthday, Babe! 🥲🫶🏼🥹🎂."

Along with Isaac, Lowry 8-year-old Lincoln with ex Javi Marroquin and co-parents sons Lux, 5, and Creed, 2, with ex Chris Lopez.

Last May, Lowry admitted that she wasn't "necessarily" interested in being a part of the franchise any longer.

"I think I need to move on," she said at the time. "I think I need to do my own thing. I think this needs to be my farewell. I think I'm ready."

Added Lowry: "I think that we should part ways. I think this should be the end."

Lowry expanded on her comments while appearing on E! News's Daily Pop, where she explained her real reasoning for leaving the popular MTV series.

"I want to focus on my self-growth and my kids and I didn't feel like the show aligned with the goals that I have anymore," she explained. "I decided it was time for me to move on."