There were no “teenagers” before World War II. Ask those still living who raised their children before then. Or spend a rainy Saturday in the basement of your library, comparing old Life magazines from before the War and after.1
Instead of Teenagers, there were Youths. Youths were young people who wanted to become adults. However confused, wayward, or silly they acted, however many mistakes they made, they looked to the future. They knew that adult life was different than a child’s life. They planned to grow up, leave childhood behind, and become adults. They were aware that life is more than youth.
The Teenager has no such horizon. Beyond the “Teeny” world there is no adult life, no past with heroes, no future with goals.