The Meaning-Making Capability

Today my desk disgorged a page from the New York Times in 2007 with this passage circled:

most people do not begin to see themselves in the midst of a tale with a beginning, middle and eventual end until they are teenagers. “Younger kids see themselves in terms of broad, stable traits: ‘I like baseball but not soccer,’ ” said Kate McLean, a psychologist at the University of Toronto in Mississauga. “This meaning-making capability — to talk about growth, to explain what something says about who I am — develops across adolescence.”

Is that the difference between middle-grade novel plots and young adult novel plots?