I was surprised when I learned that adolescence was first described in the early 20th century. That was around the same time children stopped regularly working with their parents in the family business/farm. As a society, parents have abdicated the "final transision" to adulthood to the school systems, but that isn't working, so kids have no clear path to "adulthood" and, instead, wander aimlessly. Personally, I thin…
You can't define people simply by what year they are born in. Some family environments provide children with an outlet where they end up with a very mature outlook, others don't.
The problem with this stratification is that it soon becomes the "norm" for children. My kids would say, for example, he wouldn't talk to some other kids because they are in another grade or in another class. It is a totally artificial barrier.
In days past, you'd have a grandfather or grandmother around. Kids would hang around their uncles and cousins workshops. There no distinct border. Children can see how they are expected to transition from one role to another.
Fast forward to the present day, the "teen" is now effectively a market segment, and it has become "weird" or uncomfortable to deal with kids who are too young for them or adults who are uncool for them. The narrative behind TV shows and books only serve to reinforce this.
As parents, we have a duty to help our children recognize these artificial barriers and help them overcome these perception.