I have a great grand uncle Charles Lewis Lavine (Betzalel Eliezer) of Newark NJ, who on his WWI draft card wrote his birth date as either 1886 or 1887. On the back of the card, the draft board registar wrote "claims he (Lavine) wrote to Washington DC to get his correct birthdate". At that time, both of Charles' parents were still alive in NJ, and obviously they didn't know exactly what year their son was born in. I guess he thought some official in Washington would somehow have information on the birth year (from a census?).
As it turns out, Charles' great grand niece Michele (me) found the 1888 Russian Revision list from Lida (now Belarus), showing little Tzali Lev was 3 years old, so born in 1885. So Charles wasn't too far off from the actual year. I've had other relatives who were way off, sometimes by 5-6 years.
Lak/Lok/Liak/Lock and Kalon/Kolon in Zagare/Joniskis/Gruzdziai, Lithuania
Lak/Lok/Liak/Lock in Plunge/Telsiai in Lithuania
Rabinowitz in Papile, Lithuania and Riga, Latvia
Trisinsky/Trushinsky/Sturisky and Leybman in Dotnuva, Lithuania
Olitsky in Alytus, Suwalki, Poland/Lithuania
Gutman/Goodman in Czestochowa, Poland
Lavine/Lev/Lew in Trenton, New Jersey and Lida/Vilna gub., Belarus