[aruanan]

Good point. And I also wonder how much diet plays a factor in this as well.

Probably not as much as you'd think. We're now living in a day where the "poor" are frequently obese. With the wide range of foods supplemented with vitamins and minerals and with a much wider range of foods available, even in fast food restaurants, there is far less chance now than in previous decades and centuries for someone to develop a micronutrient deficiency disease that would have an impact on mental development.

[toomuchcoffee]

A diet of Fritos and Pepsi as soon as the kid can eat and drink on his own. No vitamins or mineral suppliments because that requires paying attention to the kid.