> The differences are self evident when comparing cities such as Lagos or Zimbabwe versus Hong Kong. And nobody denies it. Yet plenty would ask to what extent

> The differences are self evident when comparing cities such as Lagos or Zimbabwe versus Hong Kong. And nobody denies it. Yet plenty would ask to what extent and how has nutrition, education (notably during development), and other environmental factors have been factored in trying to draw conclusions from that. India for example tends to score lower and that despite no lack of genetic intermingling with surrounding areas yet should anyone trying to find a cause not consider for example iodine deficiency which is more common there?