Archives

The Worry about DNA privacy and GEDmatch

Sep24

Many of my matches at ancestry.com 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 ancestry.com kits)

Sep22

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 DNA of eye color: it’s complicated

Aug25

In high school I learned that blue eyes were a simple recessive gene so two brown-eyed parents could have a blue-eyed child but not vice versa. Recently I discovered that this was wrong. Many genes are involved in eye color and with the subtle variations in eye coloring.

GEDmatch eye color prediction for me

GEDmatch.com eye color prediction for me

So I ran the fun eye color calculator at GEDmatch.com and discovered that it shows many of the SNPs involved in my eye color with the details of what they each do.

I had not realized that blue eyes are caused by the lack of (brown) melanin, so really are no color. Blue happens the same way the color of the sky does: light is bounced around in a way that appears blue according to the wikipedia article on eye color. Maybe that is why my eyes appear greenish when I wear certain green shirts and turquoise when I wear those color shirts.

If the two blue-eyed parents have their lack of eye color melanin caused by different genes then they could have a brown-eyed child. I happen to know a brown-eyed child of green and blue-eyed parents (and she looks just like her Dad so not what you are thinking). This case got me curious about how that could happen. So I googled around and found this wonderful article that explains it: http://genetics.thetech.org/how-blue-eyed-parents-can-have-brown-eyed-children

Here is my attempt to simplify the ghist of that article:

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My presentation on GEDmatch Tools is this Thursday in Carlsbad, CA

Aug19

If you live anywhere in the San Diego area, you might enjoy hearing me talk about the tools at GEDmatch this Thursday evening, August 21, at 6:30 to the DNA Interest Group of the North San Diego County Genealogical Society (known as DIGG  – click this link for location details) .  I will link to the presentation in the comments here by Thursday. Instead of powerpoint, I am using a cool online HTML 5 tool at slides.com to create the presentation. Here is one of the images I made for the talk.

Sample Admix MDLP World-22 Calculator

Sample Admix MDLP World-22 Calculator

In the left image, the pygmy is actually the smaller red slice and Sub-Saharan the larger – can you tell the colors apart? I cannot.

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GEDmatch is back up!

Jul21

GEDmatch.com is back up at last!

GEDmatch.com is the site where you can upload your DNA results from any of the three main companies and compare them to other people’s results uploaded there. I have numerous articles on GEDmatch on this site, just click GEDmatch in the tag cloud on the right or click here. There is also a guide to using GEDmatch in my downloads section.

Also for anyone in the San Diego area, I will be giving a talk on using GEDmatch on the third thursday in August for the Carlsbad group of ISOGG members. More details on that soon.

Having that site back is great news for those of us who love it!