‘Wanna feel old?’ This ‘Wonder Years’ actor is now a grandparent

Prepare to be gobsmacked, Gen Xers.

Jason Hervey, the teenage actor who played devious middle child Wayne Arnold in the "Wonder Years" television series that premiered in 1988, is now a grandfather.

Who shared the birth announcement? None other than Danica McKellar, the actress who played girl-next-door Winnie Cooper.

According to a carousel McKellar posted on Instagram earlier this week, almost all of the "Wonder Years" clan — including Josh Saviano, who played nerdy best friend Paul Pfeiffer — reunited at a Fanboy Expo convention.

Hervey, 52, is the father of fraternal twins. He posted on X for their 17th birthday in March 2017, which makes them 24 today. At the time, he wrote, "17 yrs ago today my life changed 4ever as I realized what my true purpose actually was when my twins were born."

McKellar included a photo of Hervey's daughter, Shaina Torres, in the post.

Along with the images, McKellar wrote, "Wanna feel old? My Wonder Years co-star @jason.hervey (Wayne Arnold) is a GRANDPA! ?? And ooooh my goodness his grandson Shia is BEYOND precious!!"

She called out a sweet image of actor Dan Lauria, who played the grunting, constantly annoyed patriarch Jack Arnold, holding baby Shia. "I guess he’s that baby’s TV great-grandfather?? ?? Family vibes all around!" she wrote.

McKellar, who is mom to 13-year-old Draco, noted that the baby's "wonderful mother (Jason’s daughter) let me hold him — he was crying when I got him but I was able to lull him to sleep almost immediately — a trick I learned when Draco was 4 weeks old."

A video posted at the end of the carousel showed Shia sleeping in her arms while she demonstrated her calming technique of bouncing the baby in a "U" shape.

"When my son was about 4 weeks old," McKellar explained in the video, "he was crying and we couldn't figure out what to do. But my stepmom Molly came over and she starts going like this with him."

McKellar began bending her knees, patting the baby on the back and saying, "Babies need a little bit of rhythm. Babies need a little bit of rhythm."

McKellar said that Hervey's grandson relaxed once she began bouncing him, "just like my son did."

She added, "I remember being so amazed that it worked that I never forgot it."

This article was originally published on TODAY.com