Ashkenazic Shared DNA Survey - August 2022 Update

Thank you to everyone who has contributed data about shared DNA in people with Ashkenazic ancestry!  I have 6455 data points to analyze, and that should help the entire genetic genealogy community  (I'm still collecting data--you can find out more about the project and how to contribute here).

This iteration looks at how shared DNA will differ depending on how much (documented) Ashkenazi DNA each individual has.

Ashkenazic Shared DNA Survey - September 2019 Update

An updated version of this post is here.

Thank you to everyone who has contributed data about shared DNA in people with Ashkenazic ancestry!  I have 5537 data points to analyze, and that should help the entire genetic genealogy community  (I'm still collecting data--you can find out more about the project and how to contribute here).

This iteration looks at how shared DNA will differ depending on how much (documented) Ashkenazi DNA each individual has.

There are four tables below:

• Table 1 looks at all 5337 data points, regardless of Ashkenazic percentage
• Table 2 looks at those data points where both individuals are documented to be 100% Ashkenazic
• Table 3 looks at those data points where one individual is documented to be 100% Ashkenazic and the other 50% Ashkenazic
• Table 4 looks at those data points where both individuals are documented to be 50% Ashkenazic 
• Table 5 looks at those data points where one individual is documented to be 100% Ashkenazic and the other 25% Ashkenazic
• Table 6 looks at those data points where one individual is documented to be 50% Ashkenazic and the other 25% Ashkenazic

Ashkenazic Shared DNA Survey: Data by Ashkenazic Percentage

An updated version of this post is here.

Thank you to everyone who has contributed data about shared DNA in people with Ashkenazic ancestry!  I have 4990 data points to analyze, and that should help the entire genetic genealogy community  (I'm still collecting data--you can find out more about the project and how to contribute here).

This iteration looks at how shared DNA will differ depending on how much (documented) Ashkenazi DNA each individual has.

There are four tables below:

• Table 1 looks at all 4990 data points, regardless of Ashkenazic percentage
• Table 2 looks at those data points where both individuals are documented to be 100% Ashkenazic
• Table 3 looks at those data points where one individual is documented to be 100% Ashkenazic and the other 50% Ashkenazic
• Table 4 looks at those data points where both individuals are documented to be 50% Ashkenazic

Ashkenazic Jewish Shared DNA Survey - Initial Results

Updated data here.

Thank you to everyone who has contributed data about shared DNA in people with Ashkenazic ancestry!  I have 4000 data points to analyze, and that should help the entire genetic genealogy community  (I'm still collecting data--you can find out more about the project and how to contribute here).

So far I've been going through and finding anomalies in the data and contacting those submitters (if they left email addresses) to clarify some things.

I'm going to do some deeper statistical analysis once I get the data cleaned up, but meanwhile, here is a high-level look at the data so far.  This data contains entries regardless of the percentage of Ashkenazi DNA (later posts will break down shared DNA based on how much Ashkenazi ancestry the testers have).  This is using very rough data, but I wanted to get some initial information out there to hopefully help inform people while I work on cleaning the data and then analyzing results.

Ashkenazic Jewish Shared DNA Survey

Ashkenazic Jews and those with Ashkenazic ancestry often share significantly more DNA with one another than would be expected because of endogamy; Ashkenazim all descend from a small group of people whose descendants all married one another--so we're all cousins many times over.  I've looked at how endogamy manifests in my own family (here, for example), but there are many others who have tested pairs of known relatives who could contribute data to our understanding of how having Ashkenazic DNA impacts amounts of shared DNA.

[There will likely be follow-on surveys to gather similar data on Sephardic and other Jewish subgroups.]

I was inspired by Blaine Bettinger's Shared cM Project which looks at distributions of shared DNA between people with specific known relationships.  But Ashkenazim don't always fit into Blaine's bins because of endogamy.  Getting a better understanding of how having Ashkenazic DNA impacts shared DNA should help those who are trying to understand how close an unknown match actually may be.

So I need your help to let me know how much DNA your known relatives who have DNA tested share with one another.  The more sets of known relatives and information we have about the DNA that they share we know, the better we will be able to understand how endogamy impacts how much DNA Ashkenazim share with one another.