From 1873 to 1893 to 1913, people in North America went through first the 20 years of the long depression and then the 20 years of the long boom (in Canada much better known as the Wheat or Rail Boom).
Children born early in the Era of High Modernity , say between 1870 and 1885, were old enough to fully enjoy the fruits of that long Edwardian summer of optimism and exuberance between 1893-1913.
And then were often too old to enjoy the mud (and death) of the Great War.
Those born after 1885 and on until 1900 felt cheated - they had missed the boom Edwardian Years but got to enjoy all of the mud and all of the death of WWI.