Tracing African relative based on autosomal DNA results?

Question

I DNA tested my 3 children and one son shows as 1% Benin/Togo, my ex-father in law has also tested and he shows having SE Bantu. I am guessing 1% means about 10 generations back? Between my ex-in laws and myself we have a large family tree working, but none of us can find the link.

We have a photo of a my son's great great grandmother (ex father in laws Grandmother) in the family that was always rumored to be part American Indian, but we have found that to be false since no one tested (my 3 kids, father in law and his daughter) show Native American. We are stuck on this lady too since rumor has it she was adopted. I cannot find anything on her before 1896 when she was married but the record I found on Ancestry doesn't show parents names. I can't find her on Census before 1900. Lilly Grace Taylor b. 1875 virginia, d. 1962 Virginia married Brady W. Nash. Would love some ideas on how to locate her parents and how to find where the African might come into the family line.

Answer 1

With such small percentages from these regions, there is a very good likelihood that there is no African ancestry at all – you may be looking for something that isn't there. I would avoid chasing up very small percentages that show up in your ethnic profile.

AncestryDNA calls these "Trace Regions" or "Low Confidence Regions".

The AncestryDNA FAQ states:

Most people may have a percentage identified with ‘Trace Regions’ in their genetic ethnicity results. Trace Regions are regions where the estimated range includes zero and does not go above 15%, or where the predicted percentage is less than 4.5%. Since there is only a small amount of evidence that you have genetic ethnicity from these regions, it is possible that you may not have genetic ethnicity from them at all. This is not uncommon, and as more genetic signatures are discovered with a higher confidence level, we may be able to update these Trace Regions over time.

For further information on AncestryDNA's low confidence regions see What are confidence and connection levels?

Some genetic markers for, for example, Benin/Togo may be difficult to distinguish from other places, in part because reference populations for these regions may be small. AncestryDNA's Reference Panel shows that the reference population for Benin/Togo is based on only 60 samples, and there is an estimated median 80% correct prediction rate for this region (but note the wide margin of error).

To get a better idea of your ethnic makeup, try uploading your raw DNA file to multiple different sites. There are free transfers available to FamilyTreeDNA, MyHeritage, and Gedmatch, all of which offer ethnicity percentages. You will find there is significant variability between each site.