Eh French invasion.
Why can't any of teh europeans that come in be conservative.
If you mean why are we all Democrat supporters?
Religion, or should I say Religious social conservatism.
Even staunch free-marketeers in Europe tend not to be particularly socially conservative, hence they are swayed towards the Dems.
Margeret Thatcher, so beloved by US Republicans for instance was socially conservative by UK standards, but would be a moderate or even a liberal in the GOP. As far as I know she was pro-choice and certainly not openly religious.
Conservatives in Europe are more libertarian than anything.