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The drive to explore genealogy is fueled by the inter-generational or ancestral self, and the quest for self-knowledge through knowledge of our ancestors. This helps us to understand and orient ourselves in the world and in time, which then affects confidence and decision-making in all aspects of life.
Picture, if you will, a young woman receiving her DNA results from a major testing company. All her life, she's grown up hearing stories from her parents about their Swedish roots. She fully expects to see her ethnicity report to be mostly based in Scandinavia.
An unexpected surprise appears on the screen.
The next day, she purchases a full traditional costume to reflect her Irish heritage.
It's not that simple.
In reality, when you get your DNA test results from any of the private testing companies, the ethnicity pie chart or map that is shown is not a complete or entirely accurate assessment of your ethnic roots. This might be shocking news and might even prompt you to question truth in advertising or even the accuracy of DNA testing in general.
Do not worry! What is really going on here is that the testing company is making an estimate or an educated guess about your ethnic background as compared to the testing pool they already have. The good news is that you can get a much more accurate estimate for yourself if you learn a little bit more about the science behind the attractive looking maps and pies.
What is Admixture?
Admixture is the scientific term for genetic ethnicity percentage estimates. Based on user-submitted information, archaeological samples and thorough data analysis, admixture projects attempt to approximate the origin of your ancestral lines and estimate what percentage of that DNA has been passed down to the individual tester. While admixture project algorithms are based on scientific data, they are only accurate as compared to the available DNA testers who have reported their genetic ethnicity, and the archaeological samples contributed to the project. These tools are incredibly helpful for your genetic genealogy research if you know what you're looking at and what to look for.
What can your admixture estimate help you with?
There are a few notable populations that are lacking in and could benefit from a more complete understanding of their heritage in order to build up their sense of ancestral self. Americans in general often have questions about their ancestry, since the United States is comprised primarily of immigrants who at some point or another came here looking for a better life. Usually that comes along with leaving a lot of things behind, some of which may have even been destroyed, including facts about lineage. African Americans can begin to find answers from specific admixture projects that work to pinpoint tribal groups, restoring a sense of belonging that was taken from them through slavery. Adoptees can find clues in their admixture results that can lead them to their biological families and corroborate with information in their non-identifying information documents. People with unknown parentage can get insight into what to expect when they look at their projected cousin relationships between DNA matches.
Admixture estimates can also help you to discern how many generations back your relation to specific ethnic groups might be. For example, if the DNA test you took was autosomal only, and you had an 7th great grandparent who was Native American, you may not see any measurable percentage of Native American showing up in your admixture. If you had one 5th great grandparent who was Native American, you might be able to see a small wedge of your pie attributed to Native American ancestry with certain estimates, but maybe not in other ones. If your family tree is filled with generation upon generation of Chinese ancestors, but you had one great grandparent who was from England, that would make it likely for you to see about 12.5% of your admixture represented as European. These numbers aren't set in stone due to the random distribution of DNA segments. Full siblings may all have slightly different percentages show in their admixtures. If a population that you know is represented in your genealogy doesn't show up in your admixture result, you may not have inherited that segment of your ancestors' DNA.