Edit: I would argue to the contrary, that there is a appreciable difference in average IQ between some countries which expresses itself among other things in GDP and quality of life. Perhaps the nature of this difference is based on things like nutrition, environment quality, pre-natal screening and care, so improvements in all these things will decrease the gap. If it happens that after all of that there is still a certain gap , who cares? As long as the citizens live in peace and relative prosperity.