Jon Gosselin / Facebook 1 / 10
Jon Gosselin / Facebook 1 / 10

When did these girls grow up?! Jon Gosselin took to Facebook on Oct. 8 to wish twin daughters, Mady and Cara, a happy birthday.

The girls turned 15 years old today! 15!

"Happy 15th birthday to my daughters Mady & Cara today!!!!" he wrote on his Facebook page. "I can't believe you are 15 years old! I love you and I hope you have an awesome day!"

Jon and Kate Gosselin divorced in 2009 after 10 years of marriage. Aside from the twins, they are famously parents to 11-year-old sextuplets Aaden, Collin, Hannah, Alexis, Leah and Joel.

The parents no longer speak to each other.

"I wish that things were better for the kids. It's very clear by now that I'm just trying to preserve what relationship he has with them. I do think it's best for them, but, you know, divorce is hard, period," she told reporters in January. "But it's really difficult when one parent is in the sabotaging mode. That's been difficult."

Jon, meanwhile, admitted that his relationship with his kids is "strange."

"My custody with them is just, like, go out to dinner or whatever and then go home. Their schoolwork -- they're really engrossed in school right now," he told Us Weekly last month.

The girls are also turning into quite the young women. Mady loves drama club and Cara love lacrosse. They also love to shop.

"Boys it's so easy. Boys it's like, 'You want to go play football?' Okay, awesome. 'Do you want to go fishing? Do you want to go hunting?'" he said. "But with girls it's like -- I want to go to the King of Prussia [mall]."