Thesextupletsare 15!

In celebration of their special day on Friday,Jon Gosselinwished his six youngest children a happy birthday with a loving tribute on Instagram.

“Happy 15th Birthday Hannah, Collin, Alexis, Aaden, Joel and Leah!!!! Wow I can’t believe you are 15!!!” wrote Jon, 42.

For the birthday post, Jon shared three smiling photos of himself alongside both Hannah and Collin.

Jon Gosselin/Instagram

Jon Gosselin

Jon Gosselin with son Collin.Jon Gosselin/Instagram

Jon Gosselin

AlthoughKate Gosselin, who also shares18-year-old twins Cara and Madywith ex-husband Jon,maintains full custodyof their eight children, bothCollinand Hannah live with Jon full-time.

In the fall, theKate Plus 8star’s children entered milestone years when they returned back to school: while twins Mady and Cara began their senior year, the sextuplets entered eighth grade.

Ahead of their first day back at school,Kate shared a photoof her kids in their school uniforms standing on the steps outside of their house.

“This was yesterday! Feels like school never ended…and they’re already back! #SeniorYear 😳😳 #EighthGrade #ProudMom ❤️” she captioned the smiling photo of Mady and Cara and Aaden, Alexis, Leah and Joel. Missing from the photo was son Collin, who wasenrolled in a program away from homeat the time to help him reach his full potential, and Hannah, who was with Jon.

Kate also shared a second image of the sweet note she wrote to her two eldest daughters as they began their last year of high school. “Happy 1st day of senior year! I love you sooo much! I’m so P.R.O.U.D. of you! Love, Mommy,” the note reads.

While each of her kids is beginning a different chapter, Kate is also entering a new season of life.

“I started picturing myself sitting in a rocking chair, knitting, and words like ‘old maid’ and ‘spinster’ started to come to mind, and I realized that no, I don’t want that to be my fate,” she previously told PEOPLE of the series.

source: people.com