It is Good to Share
GEDmatch.com is a DNA-sharing database with various analysis tools to help the genetic side of genealogy. It is free to upload and only takes a few minutes. There are YouTube videos that show you how to do it from whichever testing company you have used, such as from Ancestry. Ideally, you should also upload your family tree in the form of a GEDCOM file but that is not essential. Family trees assume genetic continuity in families, but often DNA shows this is not always the case.
GEDmatch provides DNA and genealogical analysis tools for amateur and professional researchers and genealogists. Most tools are free, but some are premium tools for users who support with contributions. You can use the basic tools as little or as much as you like, depending on your level of interest and understanding. The tools support all levels. There are many good blogs and websites that explain the science behind DNA matching in simple terms, but a few basic rules are all that are required to get started. The GEDmatch website has its own Beginner’s Guides.
Why Use GEDmatch?
The main reason for not sharing atDNA test results on GEDmatch is “data security concerns”. It seems that the way the FBI caught a criminal using the online database has spooked many people. This is more a reflection of the perpetrator of serious crimes making their DNA result public rather than the database used for good. Infrequently, it may be concerns about understanding the science.
While DNA testers so far appear to be content that their information sits on testing company databases, we are yet to find out how really secure Ancestry, MyHeritage, 23andMe and FTDNA databases, etc., will be over time. So why not share? If your data is not out there you will learn nothing. Most testing companies also accept free uploads of raw DNA data files from other companies. Having spent the money on a test, you can get full value out of your results by sharing. There remain many important datasets out there that could provide significant advancement on understanding of mutual ancestry, if shared. Testing for ethnicity is mostly for fun, but what else might you learn?
Recent Case Histories
The value of sharing and use of GEDmatch has been further underlined by two of my recent case histories.
The Ancestry Matching Algorithm Limitation
I had two unique matches on Ancestry managed by the same person. Interestingly, the matches were sisters which Ancestry should have also shown matched each other but did not. They were clearly matches with me and another Ancestry tester already on GEDmatch (not recognised as a match to the sisters either) and part of one of my DNA research groups.There are issues with Ancestry’s matching algorithm where matches below 15 cM are commonly missed, which is why GEDmatch is so important. These sisters (who match me at a “reasonable” 18 cM & 16 cM; the cut-off for DNA matching usually taken at 7 cM to avoid matches that may be considered random) are a new “high value” of matches for me missed by the algorithm, which leads to suspect many more matches below 20 cM are being missed.
[cM is short for centiMorgan and the unit of measurement of DNA. One can share almost 3500 cM with a parent and more than 2600 cM with a sibling, which decreases to less than 230 cM for 2nd cousins and less than 75 cM for 3rd cousins. The limit for atDNA in ancestral terms is about 8-10 generations, where DNA is preserved, but 3rd cousins may not have any DNA in common due to the random nature of genetic inheritance.]
Inferred Genetic Relationships
While the family history remains unexplained, GEDmatch has allowed us to infer relationships and list possible marker segments that may be matched with other testers. In addition to the common match on part of chromosome 1, the GEDmatch analysis also found four smaller matches between the sisters and me had that appear to be genuine and may yet help us in future investigations.
Another VENESS Connection
It never ceases to surprise how many connections it is possible to make back to my Lincolnshire families. It probably explains why Ancestry ethnicity has my origins biased towards the east counties of England. About half the 42 matches are proven one way or another.
I have previously blogged about the genetic discoveries that led to the proof about my connection to the BACON family through the VENESS family of Birmingham. The value of several people sharing atDNA data in this family group has led to further discoveries, which looks like making the Canadian WHITEHEAD family also genetically VENESS aka BACON.
Another Illegitimate Cousin
The Canadian WHTEHEADs have been stuck with their 1892 ancestor Thomas WHITEHEAD born in Birmingham, the illegitimate son of Hetty WHITEHEAD. He got sent to Canada aged 10 as part of the expatriation of so-called Home Children to the Colonies for work or adoption. Hetty got pregnant around the age of 16, and as per usual with illegitimacy no father was declared on the birth certificate. The atDNA tester matched me and my American cousin Tom (our common ancestry being my 5xgreat grandparents John BACON & Margaret ROSE in Lincolnshire). Without my match to Tom, the other relationship revealed by GEDmatch would not be realised. Again, the relationship is not recognised by Ancestry, who all three of us tested with.
There was a hawker (street seller) in the same area as Hetty (Aston & Deritend districts of Birmingham) who would be carrying the same genetic marker – John Bacon VENESS, my 3xgreat uncle. Does Thomas WHITEHEAD (pictured) look anything like a Birmingham VENESS?
The removal of orphan or poor children to the Colonies such as Canada, South Africa & Australia was often cruel and traumatic even though “well meant” by charitable organisations. The practice ended about 1930. Some had a good life and good things came out if it, despite recently highlighted scandals. On the same ship heading for Canada in 1902 was a 9-year old girl named Leah BALLARD, also from Birmingham, who was to be adopted by the HARRISON family. An obvious friendship started because the couple were married as soon as Leah turned 21.
Thank you for sharing.
Mark Grace, Resident Genealogist, Ballynoe House