Neil Patrick Harris shared an adorable message to his twins on their golden birthday Wednesday.

His daughter Harper and son Gideon, whom he shares with his husband David Burtka, turned 12 on October 12th

“Twelve years old today. Harper and Gideon are, without question, the greatest two things that have ever happened to me,” he wrote underneath a side-by-side photo of his children.

Harper and Gideon were born via surrogate in October 2010.

Since their birth, Harris and Burtka have shared their children’s lives online.

It’s like we’ve all watched them grow up over the past decade.

So it’s hard to believe the twins are just one year away from being teenagers!

“They inspire me, make me chortle, allow me to be an imperfect father, and fill me with a type of love I never knew could exist,” Harris continued with his post.

He added that while “being a parent is all-consuming, the most constantly challenging thing David and I have ever done,” it’s “so, so worth it,” he wrote.”

“The[y] are remarkable. They are my children. They are my world.”

Burtka also shared an adorable photo of the couple’s twins for their 12th birthday.

“Happy 12th GOLDEN Birthday to these incredible kids! I can’t believe how fast this has all gone!” he wrote.

“I am so proud of how you are growing up. You are sweet, caring, compassionate, creative and you have the best sense of humor. I am proud to be your dad and I can’t wait to see how the next 12 years evolve. I couldn’t ask for better kids!”

Happy birthday, Harper and Gideon! It’s clear that you both make your fathers proud.