Am I Partly Jewish? An Unexpected Turn of Events

In my previous post, I discussed using 23andMe to test the hypothesis I had about my ancestry.

I was interested in Dienekes Pontikos’s result that suggested that I am potentially Ashkenazi Jewish. My colleague, Vincent, also received this result. 

I concluded that the algorithm used did not sufficiently represent my southern European ancestry. This ancestry was inherited from one Italian grandparent.

I determined that the results were not accurate. My thoughts were incorrect.

Am I partly Jewish? An unexpected turn of events

What Did I Initially Assume?

I assumed that because Vincent and I do not fully descend from the three populations in Dienekes’s program, the algorithm was not accurate. The program focuses on northwest European, southern European, and Ashkenazi Jewish ancestry. 

I assumed that this was why we both received surprising results. After I added the french and Italian persons to my analysis, there was no evidence that I had Ashkenazi ancestry. 

Inconsistencies

After I shared my original post, a reader suggested I use the Ancestry Finder tool on 23andMe to delve into this further.

The tool allows you to compare your genomes to those with similar ancestry. If my genomes matched with someone certain they are Ashkenazi, it is likely the ancestry test was correct. 

My findings showed me that 3-30% of people with a similar genome did have Ashkenazi ancestry. I was unsure of this, but there was no reason why this would not have been correct. 

During Dieknes’s analysis of GNZ participants, he tested a larger amount of people and data. The people included those of southwest European descent.

When there was more data to look at, Vincent discovered that he did not have Ashkenazi ancestry. However, the results of my Ashkenazi ancestry remained the same. 

Given this, I used a similar method to Dienekes. I took the dataset I previously used, which included some Ashkenazi people, GNZ data, and European populations taken from the Human Genome Diversity Panel.

Studying this information I used program admixture and found parts of the ancestry that were exclusive to the Ashkenazi population. 

The graph below shows in red, the estimated number of people with Ashkenazi ancestry that were used in the analysis.

You can see two GNZ people that have Ashkenazi descent. These were myself and Dan. Dan is already aware that he is of Ashkenazi descent.