Why do people think about what they want to be when they're older at a very young age?

I don't know if this is the correct answer or not, but I think that the answer to this question is that children see lots of people with lots of different jobs, and they think to themselves,

" that job is the sort of thing that I like. I think I might try that out when I'm older. "

But I also think that parents are doing jobs aka; being a nurse, and children see what they're doing, and might want to be a nurse when they're older.