Thanks for providing such a balanced and thoughtful summary of our paper. I agree with you that there are many unanswered questions about the mechanisms and about the ultimate root cause of differences in technological development.

Japan is in our sample and the statistical finding that genetic distance and income differences are correlated does not go away, so it must be an exception to the statistical regularity. The paper contains more related to this issue. First we certainly do not claim to explain all the variation in income differences - there is plenty of room for other factors. Second Japan may have adopted the Industrial Revolution earlier than its genetic distance from the English might have predicted, but that is not in contradiction with our theoretical model (which is stochastic) where it is possible for some countries to be far genetically but close in income terms. Just not on average.

Thanks to all for commenting on my paper with Enrico Spolaore. Yours is one of the most interesting blog discussions of our paper I have come across. 
 
It is true that we are aware of Lynn's work and equally true that we "consider it so scientifically flawed as to be not worth taking seriously". This had nothing to do with tactics but everything to do with substance. We do not refer to these types of hypotheses because as we argue in the paper our data tells us nothing about the direct effect of genes (particularly data based on neutral markers) on economic performance. Instead, we argue using statistical evidence that genetic distance acts as a barrier to the diffusion of technologies broadly construed. 
 
The effect of genetic distance is not incompatible with reversals of fortune of the type noted in the first comment. If a new center of innovation springs up for whatever reasons (such as England in the late 18th - early 19th century), it is genetic distance to that center that will determine in part who gets the innovations earlier. 
 
We intend to release the data we used after the paper is published.