Quick tip – Indexes may have added information

The goal of an index is to provide an easy way to find the records. Creators of indexes will sometimes add information to make the records easier to find, even when that information is not in the original record. This can create problems if the information they added turns out to be incorrect or misleading.

A recent query in the Dutch Genealogy Facebook group provides an example.  The Gelders Archief website has an index of baptismal records. One of the entries has a child with two names: Adrianus Wolters and Adrianus Dorussen, son of Theodorus Wolters and Henrica van der Ham. What is going on? Why does the child have two different last names?

Latin baptismal record

Baptismal record of Adrianus, son of Theodorus Wouters1

If you look at the original baptismal entry, it does not mention the child’s last name. The Latin record says that on 23 February was baptized Adrianus, parents Theodorus Wouters and Henrica van der Ham. It is pretty common for baptismal records to just mention the parents and the first name of the child.

The problem then becomes: how do you index such children?

If Theodorus Wouters had a son in the time that most people used patronymics but some had solidified into hereditary surnames, the indexer can’t know which name the child used later in  life. If he is indexed by his first name only, he would not be found if you search for his full name. If he is indexed by the patronymic his father used (Wouters), you would end up with a name that the child perhaps never used. A person searching for his ancestor Adrianus Dorussen (Dorussen = son of Dorus/Theodorus) would not think to search for Adrianus Wouters.

In genealogy, false negatives (not finding an ancestor) are more annoying than false positives (having to sift through multiple results to find the right one). So the Gelders Archief chose to index these children under both possible last names: the patronymic derived from the father’s name, and the patronymic that the father used. That is why Adrianus, son of Theodorus Wolters is indexed as Adrianus Dorussen and as Adrianus Wolters.


Map of Harderwijk by Frederick de Wit, 1698. Credits: Wikimedia Commons (public domain)


  1. “Personen,” index and digital images, Gelders Archief (http://www.geldersarchief.nl : accessed 20 August 2016), scan of baptismal record of Adrianus Wouters a.k.a. Adrianus Dorussen, baptized Harderwijk 23 February 1768; citing call number 842, record group 0176, p. 43.
About Yvette Hoitink

Yvette Hoitink, CG®, QG™ is a professional genealogist in the Netherlands. She holds the Certified Genealogist credential from the Board for Certification of Genealogists and has a post-graduate diploma in Family and Local History from the University of Dundee. She has been doing genealogy for over 30 years and helps people from across the world find their ancestors in the Netherlands. Read about Yvette's professional genealogy services.

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