How old is Spencer Dutton in 1923?

If Spencer Dutton was around 8 in 1883. Wouldn't that make him 48 in 1923? Also means he fought in WWI as 42 year old. Sure officers and senior NCOs were that old, but like all wars, the vast majority of troops were in their twenties. Is the time line off? I like the Spencer Dutton character in 1923--but isn't he supposed to be a decade younger than the time line suggests? 🤔