I experienced some problems when well-meaning individuals added estimated dates to undated profiles of Holocaust victims I was working on . The standard they used was dad born 25 years before kids, but in the case of Eastern Europeans, this was not good for the most part, as men in the 19th century there were often subject to compulsory 10 year military service and were forbidden to marry during that time. Thus, many Eastern European Jews didn't seek wives until they were about 30 and frequently I found, many lost their first born children in infancy or early childhood. So, dad born 25 years before the kid profiled, was a no-go most times and may have hindered other researhers on those lines looking for dad 10 years too early