Are you leaving England and France out. England probably nver could have recovered from what they lost 1914-1918 alone.
You are of course correct. The genetic losses that Europe suffered between 1914 thru 1945, followed by modern birth control and widespread abortion has forever altered European culture. Great Britain, France, Italy, Germany, and Russia are hollow shells of what they were in 1914. For slightly different reasons so is the United States.