About 3 years ago, I became interested in genealogy research and soon after discovered WikiTree. WikiTree is a wonderful community of genealogists who collaborate to build and improve a single, shared family tree for all of humanity. At its core is a user-built database of 27 million profiles, each representing a person (users and ancestors) and containing a biography; vital record (birth, death and marriage) details; and connections to family members (parents, children, spouses and siblings).

As a Mathematician, I quickly became very interested in thinking about this dataset as a mathematical graph (or what is more commonly known these days as a network). For example, we could consider each profile to be a node and connect nodes together with an edge if they are direct family members (parent-child, spouse or sibling relationships, for example).

You can use this network to answer many questions about connectivity in the dataset. For example, the WikiTree connection finder is the equivalent of the shortest path in this network between any two profiles. And whether or not a profile is connected to the main tree is equivalent to the question: is this profile’s node in the largest connected component of the network?

But there are more complex questions you could answer with a network as well. For example:

  • What is the average distance between two randomly chosen profiles?
  • What is the average distance from a specific profile to all others?
  • Who is most “central” to the network (smallest average distance to all others)?
  • How well connected is the network? Say how many nodes/edges would have to be removed in order to disconnect two people?
  • How important are individual people or connections? How does removing a person or a connection degrade the network (disconnect people, increase average distance, etc.)?

These are all questions that can be answered by analyzing the network directly and there is a whole field of Network Theory built around answering these types of questions. Of course, before you start, you need access to the full database in order to build such a network. Luckily, WikiTree is run on a very open data model and so you can easily apply for access to weekly Data Dumps. Over the last several years, I’ve spent evenings and weekends analyzing these data dumps, producing networks and learning Network Theory in order to try and figure out what interesting things I can say about the WikiTree Network. In future posts, I will share some of the discoveries I’ve made and difficulties I’ve run into along the way.

(Comments and discussion at WikiTree G2G)

This article is part of a series on the WikiTree Network:

  1. WikiTree and Network Theory

  2. The WikiTree Network Definition

  3. WikiTree Network Corner Cases

  4. WikiTree Network Degree Distribution