You probably won't be surprised which segment of the population has the highest fertility, but what about the lowest? The US Census Bureau tracks these sorts of things in detail. So according to the Census Bureau the TFR's in 2008 were: 2.09 – All races 1.84 – Non-Hispanic white 2. read more
It is Doberman pinschers, dachshunds, golden retrievers, great Danes, Irish setters, miniature schnauzers, and poodles. It is mainly because these races have a higher tendency of hypothyroidism and that leads to fertility trouble. Luckily for us humans there are no biological races, so any question about biology and races are void. read more