How to write up a negativ DNA-confirmation

+15 votes
I'm seaching for my bio great grandfather. I have name, birth year, occupation and where he lived in Norway but have not been able to find him. Several people have directed me to a Swedish person with the same name, birth year and occupation in the same area, but I was not convinced. This person had his own family and died just 3 years after my grandfather's birth. Anyway, I managed to find a man who is the grandchild of this suspected man's brother and he agreed to take a DNA-test. IF it was the right/same man, the man who tested would be my father's 2nd cousin. They did not match (at all). The tested person however had a grandchild to the suspected father as a match which really confirms there is no connection at all between our families.

How would you write this in the bio? I tried in research notes in of my great grandfather, but if feels very confused when I read it (also when I try to explain to you above). Anyone care to check it out and come with suggestions how to formulate it as clear as can be?

Thanks, Marie
WikiTree profile: August Andersen
asked in WikiTree Help by Marie Ronnegård G2G2 (2.6k points)
Excellent question Marie!  Because negative evidence can at times be as important as positive evidence :-)
It is much easier to say there is a relationship when there is a sufficient match.  If there is no match then are other possibilities.  For example, your father and his suspected 2nd cousin might not match because the 2nd cousin has a non-paternity event in their ancestral line back to the "shared" ancestral couple.
Yes, I was concerned about that, but thankfully one of my suspected great grandfather's grandchildren had tested and matched their 2nd cousin (the person I tested) so that line IS confirmed. If related, my father and the grandchild would have been (first) cousins, but they do not match at all either.

2 Answers

+12 votes
Best answer

WikiTree's guide on the subject doesn't require anything to be written in the Biography, see

However, if you want to write a Research Note, what you've just written sounds fine, basically:

DNA confirms that August Andersen (Andersen-3787) is not a match for August Andersen (Andersen-XXXX) [I'm sorry, I can't figure out which profile you're referencing, so I can't fill in those X's with numbers]. Contact Marie Ronnegård (Ronnegård-1) if you require more information.

answered by J Pease G2G6 (8.9k points)
selected by Per-Olav Hildebrand
Brilliant idea. The person that is not a match does not have a profile yet. I will create one and write as you have suggested. Super clear.

Thank you so much!

0 votes

I hope Wikitree will develop the DNA support part and work tighter with GEDMATCH

  • The sources = the 2 tests
  • The evidence = the test result
  • then document as you do with other genealogy sources the only difference is that this is a negative evidence that will be used to reject a possible hypothesis 

My suggestion 

  1. create a Wikitree space page where you document the process so other people can understand and continue your work 
    1. Add links from your profile or include part of that Space page
  2. Upload both tests to GEDMATCH
  3. Compare the results
  4. Document 
    1. GEDMATCH numbers of the kits
    2. The result
      1. what parameters you used in comparing 
      2. shared segments
      3. longest segment
      4. date when you created the result because the algorithm for comparing is changing
    3. Your conclusion  

Best is if you do it in a way so the reader of this profile can follow the link to GEDMATCH and redo the test to see your evidence = the test result


Important is to use GEDMATCH as then you can compare better e.g.


I Sälgö-1 have a church book connection to Bildtse-2 and this connection is not seen on FTDNA as we are below some value. My understanding is that 10% of the people with the same "distance as I and Bildtse-2 has is under this limit..... 

From GEDMATCH May 2015

answered by C S G2G6 Pilot (268k points)
edited by C S

Did a check between kit  T767406 (Magnus Sälgö) and T961367 (Marie Ronnegård) level 2cM


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