Yes and No. 48.
There was never a horizon or dividing line I crossed between youth and adult. It just happened.
I'm still the same person I was when I was 10/20/30/40. Still like cool things, still confused about why we're all here.
Other than my body getting real creaky and doing all kinds of weird old things, the only real difference between youth and adult is the realization that this very thread addresses. We're all just making it up as we go. There's no such thing as "adult". There's no Council of Super-Smart People running the world.
The only thing that makes you an adult is the realization that you have to be the change you want to see in the world. That you have to be the super-smart person running things.
My kid's school just implemented an app-based pickup process this year.
You have to download an app and register your phone and email and child, then when you get in the line to pickup your child you have to press a button in the app.
I literally cannot retrieve my child from school without a smartphone.