Childhood malnutrition reduces IQ. Major childhood trauma reduces IQ. No childhood education makes you massively unlikely to grasp formal logic, Ect, ect. Most third world countries are profoundly crippling places to grow up, - The good news is that any such place that manages to not be a circle of hell for a straight 20 year stretch should see its economy do a hard takeoff as a generation reaches adulthood that was not lobotomized.