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Countries of Ancestry

From ISOGG Wiki

Countries of Ancestry (formerly known as Ancestry Finder) was a feature of the 23andMe Personal Genome Service. It was accessed from Ancestry Labs on the 23andMe user interface. Ancestry Finder Lab utilized the data collected from 23andMe customers in the survey entitled, "Where Are You From?" to chart the birth country of your autosomal DNA matches' grandparents. The purpose was to attempt to give an overview of your ethnic origins by exploring those of your matches. The feature was made available to all 23andMe customers on July 8, 2010. It was retired in November 2015 when 23andMe began to roll out the launch of a new website.

Basic View

The screenshot below shows the basic view.


The following is from 23andMe's "how does this work?" tutorial:

"You have an Ancestry Finder match when you share DNA with another 23andMe customer (ie, you have a Relative Finder match) and that person has completed our Where Are You From? ancestry survey. Here we show an example match on chromosome 20 of length 14.3 centiMorgans; the matched person said that all four of their grandparents were born in Sweden, which corresponds to all four stripes being colored green. You can mouse over the table rows or the segments themselves to explore your matches.

What does that mean? It can mean that, since all four of your match's grandparents were born in Sweden, the chunk of chromosome you share with them can only have come from Sweden, so you have Swedish ancestry yourself. Since all we know is that your match's grandparents were born in Sweden, not that they're ancestrally Swedish, it can also mean that your match's ancestors moved to Sweden, but are ancestrally from elsewhere. We're working on ways to clarify which it is, and one of the best ways for us to learn is for you to tell us about your experiences, so please do.

The contributions of all your Ancestry Finder matches are summarized in the table, showing you what proportion of your genome is covered by segments from various countries. The adventurous may wish to try the "Advanced Controls" to explore your matches further. Finally, keep in mind that this feature improves the more people take the ancestry survey, so make sure you and your friends have taken the survey, and keep checking back, because your results can improve every day."

Advanced View

The screenshot below shows the Advanced View menu.


The following is from 23andMe's Advanced View Help:

"You can use Advanced Controls to explore your Ancestry Finder results.

There are five controls:

Number of Grandparents - You can change how many grandparents of your match have to have come from the same country in order to be shown. When multiple colors (countries) are present in the same segment, you don't know for sure the origin of the segment, but you can narrow it down to a few countries. The example here shows a 12.4 cM Ancestry Finder match on chromosome 10 to an individual whose grandparents come from the United States (blue stripes) and Portugal (yellow stripes). Note the correspondence between the order of the relationships (eg, "Mom's mom"), top-to-bottom, and the order of the colored stripes, left-to-right. This person has a 50% chance of having gotten a Portuguese segment, which would be cool, and then a 50% chance of having gotten a United States segment, which could be anything.

When you allow segments having fewer than four grandparents from the same country to be shown, we change the percent genome covered in the summary table from a single percentage to a range of percentages. When a range is shown, the smaller number is the length of all the four-grandparent segments put together, and the larger number is how much of your genome would be covered if every segment that could be from the indicated country, like the segment above could be from Portugal, turned out to be from that country. The actual answer will be between these endpoints.

Segment Length - You can also adjust how long segments must be in order to be shown. The longer the segment is, the more likely it is to reflect genuine recent ancestry. The default threshold, 10cM, is pretty darned unlikely to be anything other than recent shared ancestry. When segments get down towards 5 centiMorgans, there's a chance that it's not actually recent shared ancestry that causes your DNA to match the other person, but something else, such as natural selection. Take the ancestry of these shortish segments with a grain of salt.

Melting Pot Nations - We don't show matches by default to people whose grandparents were born mostly in the US, Canada, Australia, New Zealand, or South Africa, because these often aren't super helpful for ancestry purposes. It is kind of cool, though, to see how much of your genome you share with others in the 23andMe Community, so take a look if you like..

Filter to show segments declared as Ashkenazi heritage - Checking this box will highlight segments annotated as Ashkenazi Jewish in the ancestry survey. The ancestry survey asks for people to type in additional information about their relative, if birthplace doesn't capture that relative's ancestry well. Ashkenazi Jewish is one of the more common answers to that question. In time we hope to make more of the information from the ancestry survey visible in Ancestry Finder."

Filter to show Public Matches only - This an option that was added on July 29, 2010 to limit segments shown to Public Profiles. Through this option one can click through to the profile of the matching person and request to share genomes and ancestral information if not already doing so.

More information

1. When the cursor hovers over a colored match on the chart, additional information about the match pops up, such as length of segment and grandparents' birth places. Please see example: AFCursor.jpg

2. The usefulness of this tool increases with the number of 23andMe customers who fill out the "Where Are You From?" survey.

3. Adjusting the setting to include smaller matching segments (5cMs - 9cMs) may not be as informative of recent ancestry.

4. On July 22, 2010, 23andMe updated this lab to include Public Profiles. Matches who have chosen to make their profiles public in Relative Finder and Ancestry Finder show up when you position your mouse over a segment. To change your profile to public, click this link or go to "Account", then "Settings", click on the "Privacy/Consent" tab, then click the box under "Relative Finder Options" that says "I want to make my profile publicly visible in Relative Finder and the Ancestry Finder Lab."

5. On July 29, 2010, 23andMe added the ability to download your list of Ancestry Finder matches to a csv file. The option to do so is at the bottom of the page.

Further reading