Why kids stop asking why

I’ve recently written a post in my own blog, asking a question: unfortunately it’s in Italian, so I’ll try to summarize it in English here.

Kids are born scientists: they are curious, ask questions, are eager to seek an understanding on the world around them; but then they turn into adults: most of them stop asking questions, even to themselves, stop being permeable to new knowledge, and appear to have granitic certainties which no experiment could ever shatter. Those who later turn to become scientists, will have to learn again the virtue of humble curiosity.

I wonder why. Is it a natural phenomenon of human development, because you must be certain of your arguments if you don’t want to perish in front of your opponents? Or is it the consequence of a wrong educational system, which trumps their curiosity saying “stop asking questions, learn what I tell you, unconditionally” and penalizes them when the do not brag parade enough what they have memorized?

I guess both are true, but my question is: to what extent is it a biological fact, and to what extent is it a cultural one? To what extent should we fight it teaching people evolutionary biology facts and biases, and to what extent should we fight it changing the educational system in ?