Curiosity is not the simple result of environmental stimulus. Just like the color of our eyes or of our hairs, curiosity is also geneticaly predetermined.
The Gene DRD4-7R* predisposes us to the taste of discovery, curiosity. Although, it can be not so astonishing for many people as in our languages we have many expressions that implies this belief. Indeed, we can hear phrases like “he takes his curiosity from his mother”, or “her temper from her father” etc, what is really astonishing is the link of the gene and therefore this personality, with IQ and longevity.
The gene naturally predisposes human to social activities, intellectuel disciplines and sports as well. In short, this gene is found in people commonly described as active. In this case, the gene DRD4-7R prolonge the life expectancy.
In conclusion the chain of causality that leads us to be active and more or less long living is composed by environmental stimulations, but firstly by our genetical predisposition. As our genetic capital is constituted by our ancestors history, and as environnemental stimulus is also the result of a chain of causality that goes way before our own birth, indeed, the chain of causality that explains the rain of today starts way before the rain itself (cf : theory of chaos, butterfly effect), we easily understand that our personality and our life is in a way “written” before we were born.
*source : http://www.jneurosci.org/content/33/1/286