Saturday, 15 July 2017

Discovering a DNA cousin through Wikitree and confirming with GedMatch

In the year since we received our autosomal DNA results I have explored various tools to help me keep track of the results: to help me find new cousins with whom we share DNA and to show how our document-based trees connect.

One of the tools I have used is wikitree.com. Wikitree is a single tree grown using traditional genealogical sources and DNA. It currently has more than 14.6 million profiles added by more than 430,000 genealogists. Wikitree has some useful DNA tools to help make sense of your DNA results.

screenshot of the front page of wikitree.com



I have added information about our direct forebears to Wikitree. I added each forebear manually, and this meant revisiting the facts and checking that I had reliable sources for dates, places and relationships. I did not merely upload a GEDCOM file. I wanted to review relationships and I did not want to create duplicates. Wikitree has a single profile for each person. It is important to remember that none of us own our ancestors and we need to work with others on the information we attach to each profile. In fact we benefit from working with other descendants.

In addition to adding your forebears to Wikitree, you can add details of the DNA tests you have taken. Wikitree adds the information that you have taken the test to all blood relatives within eight degrees of separation — up to sixth great-grandparents and out to third cousins. You don’t upload the contents of the DNA results, just the fact that you have taken the DNA test and information that will help potential matches find you in each testing company’s database.

Recently I was contacted by Simon Bass, a distant cousin, who has also been adding his forebears to Wikitree. (Note Simon reviewed this post as a draft and following publication and is happy for me to blog about this case study.)  Simon has found that he seems to have a DNA connection to my husband’s family. Both my husband Greg and Greg’s brother Dennis have had their DNA tested and added their information to Wikitree. Simon is descended from Elizabeth Gilbart née Huthnance (abt 1774-1847) and her husband John Gilbart (abt 1761-1837). When adding their daughter Catherine’s details to the tree, linking Catherine to Elizabeth and John who were already on the tree, Simon noticed that Wikitree had a section on DNA connections on the right hand side of the screen.


Wikitree profile of John Gilbert (abt 1761-1837) retrieved from https://www.wikitree.com/wiki/Gilbart-8 on 15 July 2017. (click to enlarge)




Simon wrote to me and, despite testing with different companies, we were able to compare our kits on GedMatch.com . Our biological cousinship was confirmed.

GedMatch.com provides DNA analysis tools for genealogists including tools for comparing your own DNA test results with those of other people in the GedMatch public database. To use these tools you must first upload your DNA test results to GedMatch. GedMatch accepts results from Ancestry.com, Family Tree DNA, MyHeritage, 23 and Me, and WeGene.

GedMatch one to one comparison of DNA shared by Simon Bass and Dennis Young. Simon and Dennis share DNA on two chromosomes. Based on the size of the match it is estimated that there are six generations to their most recent common ancestor. Their relationship based on our document-based family tree is 5th cousins which is six generations to the most common recent ancestor, the prediction based on shared DNA is in line with our genealogy.


Since this first exchange of information Simon has shared photos with me of his trip back to St Erth in Cornwall, where the Gilbart and Huthnance families came from. We have also exchanged notes on the emigration of various members of the Gilbart family to Australia.

Wikitree made it easy for us to see that our document-based trees connected and showed that we had taken DNA tests. Having uploaded our test results to GedMatch.com, we could compare test results and see if there was a likely biological connection.

If there had been no shared DNA it would not have disproved that there was a relationship. It just meant that the same segments of DNA had not been inherited by Simon and his cousins Greg and Dennis.

Simon, Greg and Dennis are 5th cousins since they share 4th great grandparents. There is a nearly 70% chance that any two fifth cousins will not share a detectable level of DNA. ( https://isogg.org/wiki/Cousin_statistics ) In fact Greg’s brother Dennis shares DNA with Simon but Greg does not.

Related posts

No comments:

Post a Comment