Isolating DNA segments related to specific ethnicity-location

Question

Almost all genetic genealogy websites will tell you the origins of your DNA. But I would like to go one step further and find out which parts/segments of my DNA are related to a specific ethnicity.

I have a very rough map of my DNA -- as it relates to shared common ancestors for my matches. If I could isolate specific segments for a specific locale, I might be able to link this to an ancestor. For instance, I am told by several sites, that I have about 20% scandinavian DNA. Is there a way to find which part of my DNA is Scandinavian? (I'm assuming that if this can be done, it will be with a tool on GEDmatch.com.)

Answer 1

Specific ethnicity reports are very misleading, as the field is very new. And Scandinavian DNA has been notoriously over-reported from the beginning. It's fun to play with the tools and reports, but don't be surprised if your ethnic roots change over the next few years. :-)

Go to GEDmatch.com

Click "Admixture (heritage)"

Check "Chromosome Painting - Reduced Size" then select "Eurogenes" and click "Continue"

Select "EUtest" and enter kit number, then click "Continue"

Answer 2

23andMe will do what you wish and tell you what parts of your DNA they matched to each ethnicity they found for you.

They will not provide you directly with the exact segment data, but if you inspect the source of the web page that produces the information for you, you can pull out the numbers they use, e.g.:

The above lines says that the unassigned section on Chromosome 1 starts 26.7502% the way across and continues another 3.01663%. You could multiply these percentages by the chromosome length in base pairs (Bp) and then see which matches lie within the ethnicity regions.

If you do chromosome mapping and have mapped your chromosomes to your ancestors, then the ethnicities of the segments should relate to the ancestors you have mapped on the segments. Of course, this will only be as good as the ethnicity results are, which likely are not too accurate at this level of detail.