It's a half-true stereotype. I work with people who basically do almost nothing but code or talk about code... and they're in their late 20s and 30s. I've been on dates with software engineers who bring tech stuff to the conversation a little too often for my tastes as well.
Young teens are more obsessive about hobbies so if you're really into computers at that age, that's all you do.
In the real world though, for every person like that, there's ~10 who either don't think about code after 5pm or aren't nearly as obsessive. But it's definitely a thing in our industry!
I used to be like this then my interest broaden a lot when I was about 22. I basically have friends now that I only talk via chat or when I want to talk tech since my old crowd would just chat about it perpetually.
Young teens are more obsessive about hobbies so if you're really into computers at that age, that's all you do.
In the real world though, for every person like that, there's ~10 who either don't think about code after 5pm or aren't nearly as obsessive. But it's definitely a thing in our industry!