The big currencies like the euro and dollar mostly do. That's not to say that government and central bank policy doesn't have an effect, central banks influence

The big currencies like the euro and dollar mostly do. That's not to say that government and central bank policy doesn't have an effect, central banks influence rates with interest rates and quantitive easing, during the Bush presidency a law he passed regarding taxation levels on profits held outside the US contributed to the dollar strengthening. But the degree to which the dollar, euro and pound can fluctuate vs each other is massive compared to the yuan.