The genealogical certificate (Abstammungsurkunde) was a 'civil status' document made under German law. It was created to prove the birth of a child and it differed (ever so slightly) from a actual Birth Certificate.
It's main purpose (of the genealogical certificate) was to determine marriage bans with adopted children. This became just another example of excess paperwork, and the genealogical certificate was abolished in Germany on the 1 January, 2009 by the 'Civil Status Law Reform Act'.
So. Genealogical certificates were issued up until the 31 December, 2008 by the civil registry office that had certified the birth. Contained on the certificate, amongst other things, was the name of the child, the child's sex, date of birth, place of birth, and the parents' names. Also contained on the certificate were any changes listed that may have occurred since the birth of the child, for example, the adoption of the child and/or any name changes.
Genealogical certificates were a bonus, as it was those documents that actually reflected the descent of a person. A requirement for marriages was a genealogical certificate, as it only it showed who the biological parents were. Birth Certificates only show the legal parents, which in adoption whould name only, the adoptive parents.Since 1 January, 2009, a "certified register printout of birth registration" is required upon marriage, which also contains information about the birth parents. This differs from the birth certificate as discussed..
The biological fatherhood of the alleged biological father is not assured when printed in the aforementioned genealogical certificate or "certified register of birth."
Source :https://en.wikipedia.org/wiki/Genealogical_certificate accessed 10 October 2016