I'm not sure whether I agree with all of the author's conclusions either. Still, it's interesting that rich people were having more children during this time period.
It's also interesting that the same pattern did not show up in Japan or China. Why? Were the rich there not genetically superior enough?
In today's world, the rich have fewer children than the poor. Perhaps the Japanese and Chinese were ahead of their times, or maybe the rich there had some understanding of birth control.