Most of my matches at ancestry don’t see why they should upload their data to GEDmatch. I send them the URL of my slide presentation and extol the delights of the fun ancestry composition (admix) tools but it is hard to explain why I like to see where my DNA matches someone else’s. Curiosity? It’s fun? I love making these spreadsheets? Possibly it is because I am very interested in how DNA inheritance works and love to see which grandparent gave me which piece of DNA (n.b. it takes a lot of work to get to that point).
When I know the common ancestor for a specific segment sometimes a new match fits in immediately to a family line. The best example of that is finding my previously unknown 3rd cousin Katy. When I saw where she overlapped I emailed her that it looked like she was related on my WOLD line to which she responded that her grandmother was a Wold. She has since sent me many wonderful family pictures that I had not seen before.
Today I got an email from someone who had tested at ancestry and uploaded to GEDmatch. She wanted to know how to use my tools with her GEDmatch data. However my tools require a CSV file of overlapping segment data which cannot be downloaded in one fell swoop from GEDmatch, unlike at 23andme or Family Tree DNA.
Personally I built my many CSV files (one per person tested) slowly, as I compared each individual’s DNA results, contacted that match, and then cut and pasted the overlap information into my spreadsheets. Jim Bartlett did a great guest blog here on the process of building these DNA spreadsheets.
But I can understand the desire to see a quick picture of your matching DNA. GEDmatch does have a chromosome browser where you can see the overlaps, although the presentation is somewhat different from other sites. A little known secret is that you can massage that function’s table output into a spreadsheet (see end of this post for the technique).
