Are the Birth Dates of Our Ancestors Real? Registration of False Birth Dates in 20th Century Poland

Jacek Cypryjanski , University of Szczecin
Marta Hozer-Kocmiel, University of Szczecin

Falsification of birth dates, i.e. registration of a date other than the actual date of birth, was first observed in Italy in 1895/96 by R. Benini and then in many other countries in the world at the beginning of the 20th century. The aim of the analysis presented in this paper was to explore the phenomenon of registering false birth dates in 20th century Poland. The study was conducted on the basis of birth dates of 44,187,032 Polish citizens born in the years 1900–1999, and registered in the General Electronic System for Registration of the Population (PESEL). Two types of falsifications were observed: (P1) registering children born in December as being born in January of the following year and (P2) registering children as being born on specific days of the year, month or week. The size and duration of each of these phenomena were estimated.

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 Presented in Session P1. Poster Session Fertility, Family and the Life Course