They grow so fast! Fans have literally watched Kate Gosselin and Jon Gosselin‘s twins and sextuplets grow up on TV, from their Discovery channel specials to the family’s now-defunct reality TV series, Jon & Kate Plus 8 and the spinoff, Kate Plus 8. On May 10, Jon and Kate’s sextuplets turned 15 years old and the 44-year-old mom of eight took to Instagram to commemorate their big day.

“Our big celebration of #15 is finally winding down here! We celebrated ALL DAY LONG, beginning with a present at 6:30 am before school!😳 I’m so very thankful for my ‘babies’ … somehow they are 15 already?! I’m amazed by them each day! I’m so proud of the positive qualities I’ve seen developing as they edge closer to adulthood,” Kate gushed in her caption on Instagram. “It hasn’t been easy for them, especially over the last year and a half, but they continue to persevere, stay positive and make lemonade out of lemons (to the point where I’m pretty sure I’m allergic to lemons, but what’s a mom to do?!🤯) But no matter what, these kids keep on keeping on! Such good, wholesome, loving, insightful, wise humans and I’m just so proud to call them mine! I love you guys to the moon and back a hundred billion times x infinity😉! Happy 15th birthday! 🥰🥳🎂😘😍 #15 #Lemonade.”

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Our big celebration of #15 is finally winding down here! We celebrated ALL DAY LONG, beginning with a present at 6:30 am before school!😳 I’m so very thankful for my ‘babies’…. somehow they are 15 already?! I’m amazed by them each day! I’m so proud of the positive qualities I’ve seen developing as they edge closer to adulthood. It hasn’t been easy for them, especially over the last year and a half, but they continue to persevere, stay positive and make lemonade out of lemons (to the point where I’m pretty sure I’m allergic to lemons, but what’s a mom to do?!🤯) but no matter what, these kids keep on keeping on! Such good, wholesome, loving, insightful, wise humans and I’m just so proud to call them mine! I love you guys to the moon and back a hundred billion times x infinity😉! Happy 15th birthday! 🥰🥳🎂😘😍 #15 #Lemonade

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But fans were quick to point out that only four out of Kate’s sextuplets were included in the photos from her birthday celebration post — Alexis, Aaden, Joel and Leah. The other two of the bunch, Hannah and Collin, live with their dad Jon, 42, after he won custody of both kids in 2018.

“Ummmm I only see 4/6????” one fan pointed out, and another commented, “They need Hannah and Collin!!!!”

Meanwhile, Hannah and Collin were able to enjoy a birthday celebration over at their dad’s house and Jon took to Instagram to share his own tribute to his youngest children. “Happy 15th birthday Hannah, Collin, Alexis, Aaden, Joel and Leah!!!! Wow, I can’t believe you are 15!!! Time is flying by!!! I love you all very much. I wish you the best day ever and I hope you enjoy your birthday celebrations today and this weekend!!! Love always, Dad.”

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