John Stamos is congratulating Full House co-star Ashley Olsen on the birth of her first child!

Last week, it was announced that the 37-year-old fashion designer had welcomed her first child, a baby boy named Otto, with husband Louis Eisner.

Taking to his Instagram, John, 60, sent his love to the new parents, while also sharing some adorable throwback footage and photos of Ashley and twin sister Mary-Kate Olsen from when they were kids on set of Full House.

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“Watching Mary-Kate and Ashley grow into the incredibly bright and remarkable women they are today has been one of the greatest joys of my life,” John wrote. “If you would have told me those blue-eyed babies I met on set nearly 40 years ago would still be in my life at 60 years old, I wouldn’t have believed you. I am blessed. Congratulations to Ashley and her husband, Louis, who welcomed their baby boy last week.”

In the video, John included a voiceover of him reading a passage from his upcoming memoir If You Would Have Told Me where he recalled the last casting calling for Michelle and how it went to Mary-Kate and Ashley, who “big blue eyes wide with wonder.”

“Right away, I know the relationship between Jesse and Michelle is an important one,” John reads. “But as the show develops, the connection grows. I’m young, but I really want kids someday. And these lovely little girls—so bouncy and bright—represent the best versions of future dreams.”

In a recent interview, John revealed how he briefly got Mary-Kate and Ashley fired from Full House.