Kate Hudson can't believe she's the mother of a 20 year old — and honestly neither can we. In a new interview, Hudson opened up about her son Ryder Robinson turning 20 last month and how she was only "a couple years older" than that when he was born.

"That's been the wild discovery for me," Hudson told People. "I just can't believe that I was only a couple years older than him when I decided to have a child."

"The fact that we've been able to get through it together like this, and really, honestly, grow up together, has been incredible," she continued.

Hudson, 44, has been so busy being a mother to Ryder (whom she shares with ex-husband Chris Robinson) — as well as son Bingham from her engagement to Matt Bellamy, plus her and fiancé Danny Fujikawa's daughter, Rani —that she didn't realize just how fast time was moving.

"I guess while raising him, [I was] just in it and present, and then they fly the nest, and they're sort of cooked — and they're adults!" she told the outlet. "You look back going, 'Wow, I can't believe [it].' "

Hudson added that Ryder is "in a great place" and "enjoying his life" as he leaves his teen years behind. But, she does have one qualm about him entering adulthood.

"I wish he lived a little closer," she told the publication. "But I just love seeing him explore his adulthood. He's an adult, you know? He's out in the world and doing his thing. ... We're very close and I'm very proud."

Ryder celebrated the milestone birthday on January 7, and Hudson shared a sweet Instagram tribute that contained an image of a birthday cake with an old photo of Ryder as a youngster and gold "2-0" candles. "I’m gonna have to let this one digest for a bit..: 😭," she captioned the post. "My beautiful boy, happy 20th. I love you beyond."