In April 2018, we updated the Ancestry Composition report to include new regions — your recent ancestor locations — from around the world. These regions will provide you with information about your more recent ancestry, giving you insight into where your ancestors likely lived during the last 200 years.
Assigning Your Locations
Recent ancestor locations (found in your Ancestry Detail reports) are intended to complement your ancestral breakdown and provide a more recent and granular view of your ancestry. To determine these results, we look for identical pieces of DNA that you have in common with individuals of known ancestry from around the world. Reference populations for recent ancestor locations consist of over 400,000 customers, and this number will continue to grow as our customer database expands.
In order to be assigned a recent ancestor location, you must share identical DNA segments with people of known ancestry from that location. Importantly, we don’t include close relatives (i.e. first cousins or closer) in this calculation, and these matching DNA segments must be unique, meaning we do not double-count identical segments you might share with multiple distant relatives. These initial steps determine the percent genome shared between you and the reference individuals for each location.
Next, we do a calibration step to set more meaningful thresholds that accounts for the special demographic histories of each location. This calibration step helps determine whether you share a similar genetic makeup to people who have recent ancestry from a specific location. We then use this comparison to set unique confidence thresholds for each location.
The strength of the match for each recent ancestor location is determined by how much of your DNA you share with people from that country, calibrated by how many people are in the reference population. For a given recent ancestor location, we indicate our confidence in the result. "Possible" means we are between 30% - 49.9% confident in the assignment, "likely" means we are between 50% – 79.9% confident, while "highly likely" means we are at least 80% confident in the assignment. "Not detected" means we are less than 30% confident in assigning that recent ancestor location to you.
Ancestry Detail Reports
The maps on your Ancestry Detail Reports are a visual representation of your recent ancestor locations down to the state and county level. A map is generated by aggregating the ancestral origins of individuals who share a minimum amount of DNA with you.
Why don’t I have any recent ancestor locations?
If you don’t share the minimum number of identical DNA segments with our reference individuals and/or the percent of your genome shared with our reference individuals does not pass our confidence thresholds, then you will not see any additional regions added to your Ancestry Composition report. Keep in mind that Ancestry Composition can be considered a living analysis, so you may see recent ancestor locations added in the future as new matches are detected or as new regions are added.
A high percentage of my DNA is assigned to a particular reference population. Why don't I have high Match Strength with any of the countries listed?
To assign your recent ancestor locations, we look for identical pieces of DNA that you have in common with a large group of individuals with known ancestry from many regions worldwide.
The more DNA you share with reference individuals from specific locations, the higher the likelihood is that those locations will be assigned to you. However, you may not have enough genetic relatives with self-reported ancestry from a particular country or region for us to assign that location to you with confidence.
The likelihood that a recent ancestor location will be assigned to you depends on other factors as well, including the region’s genetic history. For example:
- On average, people from a smaller, more homogenous country like Iceland will share more DNA with each other than people who come from a larger, more diverse country like China. As a result, it may be more difficult for us to identify ancestry from certain countries than from others, depending on their population history.
- Additionally, if you are from a group within a country that is not common in our reference dataset or is very genetically similar to other countries for which we have larger sample sizes, it is less likely that you will get a match for the recent ancestor location you expect.
- Country borders have changed a lot even within the past 100 years, which can sometimes produce confusing recent ancestor location results. For example, country borders in Eastern Europe and the Balkans changed dramatically with the dissolution of the Soviet Union in the last decade of the 20th century.
I have a parent genotyped. Do you know which side of my family a recent ancestor location came from?
No, while we can determine that a match exists to one of our recent ancestor locations, we don't know which copy of a chromosome (or, which side of your family) that match occurs on. This is because your phased chromosomes are not used to find matches.
Will you add more recent ancestor locations over time?
Yes, we hope to add additional regions in the future. You can consider your Ancestry Composition a living analysis, so your report may change over time. If new matches are detected or new locations are added, these will be added to your report.