Long before Instagram, the biggest celebrities of the 90s and 00s reserved their pregnancy announcements and baby photoshoots for magazines. We still remember THATVanity Faircover where Katie Holmes and Tom Cruise showed off a newborn Suri Cruise (with a full head of jet-black hair.)

But fast-forward a decade or two and many of those babies are now teenagers who are learning to drive, finishing school and even following in their famous parents' footsteps.

While some of their parents share their kids' birthdays and exciting milestones on social media, it's still a shock to see how much they've grown.

Watch: Here's what your favourite celebrities got up to in isolation. Post continues after video.

Earlier this week, Reese Witherspoon shared a photo of herself and her eldest son Deacon on Instagram, for his birthday. And the newly turned 18-year-old looks so mature it's frightening.

"How did this happen?!! @deaconphillippe is 18?!! One day he was trading Pokémon cards, singing Bruno Mars songs, and playing American Ninja Warrior in the backyard," Witherspoon, the mum-of-three wrote.

"The next day, he is taller than me, cooking the family steaks on the grill and making his own music with his best friends. My heart is bursting with pride about the young man he is becoming. Happy 18th Birthday Deacon! I love you to the moon around the sun and all the stars."

So what do other celebrities' children look like now? Here are 16 of them.

Apple Martin

In April, Gwyneth Paltrow told her millions of Instagram followers that she'd be launching some new Goop products. For the announcement, she shared a rare photo of herself and 17-year-old daughter Apple Martin.

And of course, she's the spitting image of her mum.

Leni Klum

Heidi Klum's daughter Leni not only looks just like her mother, but she's also getting into the same industry. In December 2020, the 17-year-old made her modelling debut alongside her mum on the cover ofVogue Germany.

Sharing the news to Instagram, Leni wrote: "So excited for my first cover!! I had so much fun on set with @voguegermany couldn’t dream of a better start!! Thank you for being by my side @heidiklum."

Speaking to People, Klum explained that she feels Leni's old enough to enter the industry.

"I always thought she was too young. We always also