@Ia_N4m3_T4k3n
For me: I usually have 2 separate ages: their actual ages and then their "human" age which slows or quickens up depending on how developed their going ((So America was frankly almost the same age as his father during WWII))
England is one of the oldest alive and active with her human age around her 50's to 70's while her son Britain is about 35
USSR's kids are only Russia, Belarus, Ukraine and Transcaucasian (The mother of now Georgia, Armenia, Azerbaijan) and so their where at best late teenagers to their full grown 20's everyone else was invaded
With N#zi and his father: N#zi was actually almost mid 20's and was much older then the age most kids who try to get their independence ((22 years old)) so his movement seemed unlikely
Most of them are just smaller forms of government.
Most of them die at the hands of their own kids, get separated, become the smaller form of government or go insane (A.H.Empire)