Archive | September 2014

The Worry about DNA privacy and GEDmatch

Many of my matches at are afraid to upload their raw data to GEDmatch because of their fears about DNA privacy. Here is what I want to say to all of them.

DNA imageThese personal genome tests are not your full genome, just a sampling of the places you are likely to be different from the next person. Remember that we all share 98-99% of our DNA with every other human being.

There is not enough information in these tests for some future mad scientist to make a clone of you.

The GINA law protects you from insurance companies or employers using your DNA information to discriminate against you or deny you health coverage.

So are you afraid that someone will know your blood type or eye color? What about unusual medical conditions? They can only figure something out about you if they know the kit number of someone with your same traits. All they get to see is where the DNA overlaps with another kit, not the raw data itself. And they would need far more knowledge about DNA than the average tester has, to use those overlaps to figure out anything about you.

A prominent genetic genealogist with a PhD in biology, Blaine Bettinger, has so little fear about people seeing his DNA data that he posted it all online for anyone to download and look at!

Your identity cannot be stolen from this data sampling of your DNA. It is like a giant fingerprint not a credit card number.

On the other hand, if you have any criminals in your family it is just barely possible that your DNA could help track them down. Not a good idea to do DNA testing if you are a criminal yourself, although the FBI uses different markers than what these tests look at.

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The GEDmatch Chromosome Browser (for my cousins with kits)

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).

MyGEDmatchSlidesWhen 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).

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The TV show Finding Your Roots is back!

The new season of Finding Your Roots is coming to PBS next Tuesday night at 8:00 P.M. so set your DVRs to record it. My friend, genetic genealogist Cece Moore, is the DNA consultant for the series. She kindly gave me permission to use this great photo of her at work with Henry Louis Gates, Jr.

CeCe Moore at work with Henry Louis Gates Jr

CeCe Moore at work with Henry Louis Gates Jr

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Using the Chromosome Mapper to make a four generation inheritance picture

My friend Angie Bush is a most creative genetic genealogist whose daughter Brynne is apparently following in her footsteps. They do a lovely presentation on autosomal DNA together which includes this slide showing four generations of DNA inheritance, made with my ancestor chromosome mapper.

Three generations of DNA to Brynne

Four generations of DNA to Brynne (click to see a larger version)

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