Conservatives are having more children than Liberals according to this research, which has some interesting implications;
The greatly expanded childless segment of contemporary society, whose members are drawn disproportionately from the feminist and countercultural movements of the 1960s and '70s, will leave no genetic legacy.
There seems to be a suggestion that conservatives will breed carbon copies of themselves but then, where did the "feminist and counter-cultural" ideas come from? Children with conservative parents?
There is also no mention here of the much higher US fertility rates among hispanics and blacks who are more likely to vote democratic, which by my definition makes them Liberals.
Use the graph to work out when Thatcher was in power
7 minutes ago