"Resolution" of DNA testing

Question

What is the spatial/cultural "resolution" of DNA testing for genealogical purposes? How finely can it be used to estimate where a particular person's ancestors were from? I am interested in testing the hypothesis that some of my wife's ancestors who came to the US from the Ukraine had previously emigrated from Germany to the Ukraine. My hypothesis is based on their last names (which are more German-sounding than Russian or Ukrainan), but I am wondering if it would be possible to refute or corroborate it using DNA evidence.

So the basic question is this: does the DNA of Jews from the Ukraine differ from the DNA of Jews living in Germany, and can this difference be detected reliably?

Answer 1

A DNA test will reliably distinguish between members of two populations:

1. if the populations had distinct ancestors
2. or they have been isolated for a very long period since their last common ancestors
3. and a characteristic non-deleterious mutation occured in only one population
4. and that mutation has become widespread and stable within the population
5. and the test you have carried out reliably detects that mutation
6. and a critical mass of members in each population has had the same test to provide reference data

In the case of central and eastern european Jews, your starting assumption is that (1) does not hold. So for (2) to apply, you need the migration path of those in the Ukraine to have NOT passed through Germany. The improbability of that reduces the time for (3) and (4) to occur.

The good news is that the recent focus on genetic genealogy in these communities gives you fair chances of (5) and (6).

However, since the probabilities are multiplicative, the overall chance that you will get a definitive answer that "the family moved from A to B within the last n generations" is quite small.

Do not abandon document-based studies just yet.

Answer 2

So the basic question is this: does the DNA of Jews from the Ukraine differ from the DNA of Jews living in Germany, and can this difference be detected reliably?

To answer very simply: No.

There isn't any discernible difference between the DNA of Ashkenazi Jews who lived in one country vs another. Ashkenazi Jews always have DNA matches with other Ashkenazi Jews from a wide variety of countries.

However, if there are German-Jewish families with the same surname as your wife's family, then Y-DNA testing could prove useful. You would need a living male with the surname from both families to take the Y-DNA test. If their Y-DNA results match, that would at least prove that the two families have a common patriarch. Whether the common patriarch lived in Germany or not is still something you would need to figure out by paper trail.

Answer 3

There is a coordinated effort going on now at the JewishGen website, where they are using the services of Family Tree DNA to help Jewish Genealogists identify their origins.

There are many projects going on (e.g. Surname projects) which include a collection of Regional Geographical Projects, one of which is a German-Jewish SIG.

They would not be doing projects by location unless they believed the DNA could ultimately locate people. They have provided tools for each SIG to map the ancestral locations of those who had their DNA tested, versus their Haplogroup.

And latest research in Epigenetics indicates that environment does not change the genes themselves, but can affect how they are structured. This information can be detected and can potentially identify locations, habits and lifestyles of your ancestors.

Regarding your question whether the slight difference in location (Germany to Russia) for Jewish people can be detected reliably yet: It is possible, but it depends how much Jewish data has been collected for the two areas that can be related to your DNA test.

For example, the FAQ of Family Tree DNA says:

13 . Where did my ancestors come from?
We provide three tools to help answer this question for your direct maternal line. While you are logged in to your myFTDNA account:

• Check the haplogroup name and description on your mtDNA Results page. This will provide background to your historic ancestry and origins.
• Check the mtDNA Ancestral Origins page. This includes places where your DNA motif can be found today. It is influenced by more recent migrations.
• Use the myMaps tool to see a map you and your match's most distant known ancestors and locations.

and

33 . What will the mtDNA Refine test tell me?
The mtDNA Refine test adds the second hypervariable region, HVR2, to your test results. That is the portion of your mitochondrial DNA that runs from nucleotide 00001 to nucleotide 00574. Your matches to others in the same haplogroup on both HVR1 and HVR2 have a 50% likelihood of sharing common ancestry with you within twenty-eight generations. That is about 700 years. If you also share ancestry from the same location, the same village, town, or city, then you likely share common ancestry within recent times.

The way to see if your wife's ancestors may have come from Germany is to join the DNA SIG for their surnames. If you find a DNA match with someone else with the same surname, and if they know their ancestors to have come from Germany, then that could indicate possible relatives in Germany and would suggest that your wife's ancestors were in Germany prior to Russia.