AncestryDNA Explained – How to use Your ANCESTRY DNA Results

by | 5 Dec 2020

Your AncestryDNA results are back, so now what? Whether you ordered an AncestryDNA test for yourself out of curiosity or received it as a gift, it’s common to be overwhelmed when the results come back. There are ethnicity estimates, DNA matches, and ThruLinesTM, plus analysis tools and search features — it can be a learning curve for even seasoned genealogists.

The AncestryDNA test is an autosomal DNA test (atDNA), which examines hundreds of thousands of positions, or markers, on chromosomes 1-22 plus the X-chromosome to provide information about relationships and ancestors from both sides of your family tree. These markers are locations where people’s DNA often differs slightly, called Single Nucleotide Polymorphisms, or SNPs (pronounced “snips”). We inherit our SNP versions from our parents, meaning that we will match with our close relatives at many of these SNPs while sharing far fewer matches with distant relatives. In other words, the number of matching SNP locations can help to determine how closely related two people are.

What AncestryDNA does NOT do, however, is test your mtDNA (maternal DNA) or your Y-DNA (Y-chromosome DNA), nor will it provide you with information on your maternal or paternal haplogroups.

Ethnicity Estimates

DNA variants occur at different frequencies in different geographic regions around the world. To determine what regions your ancestors came from, AncestryDNA analyzes your unique set of DNA alleles against a set of geographic reference panels (people whose families have lived in one region for generations) to determine your genetic similarity to various worldwide populations within the past ~300–1,000 years. Because many people today have ancestry from more than one population and/or location, you’ll often see the specific combination or “mixture” of genetic populations from which you descend referred to as your admixture. AncestryDNA calls this your Ethnicity Estimate or DNA Story.

Genetic Communities

While ethnicity estimates are focused on distant ancestry, Genetic Communities are “clusters of living individuals that share large amounts of DNA due to specific, recent shared history.”1 Clusters are based around people in AncestryDNA’s network who share genes in common with most if not all others in the group; each cluster is then assigned to a specific geographical location utilizing both the ethnicity data and family trees of everyone assigned to that cluster. As new people test with AncestryDNA they are assigned to one or more of these clusters based on the DNA they share with other AncestryDNA members. Communities reflect your recent heritage, including not only where your ancestors may have settled, but where they may have come from. And because they are based on both DNA matching and user-generated trees, Genetic Communities are generally pretty accurate.

DNA Matches

While curiosity about ethnicity is what first attracts many to DNA testing, one of AncestryDNA’s most informative features is DNA Matches – a “match list” of other testers, or genetic relatives with whom you share DNA. AncestryDNA compares your DNA to the results of every sample in their database of over 15 million testers, looking for segments of DNA that you have in common with others in the database. Once a match is identified, AncestryDNA uses the amount of DNA you share to estimate the genealogical relationship between you and your match (e.g., sister, uncle, grandparent, 2nd cousin once removed). Results are arranged with your closest relatives first, then working through the list to distant relatives (4th cousins and beyond). If you build a family tree on Ancestry and link it to your AncestryDNA results, you’ll also see a common ancestors hint when you and a DNA match both have the same ancestor in your trees. A variety of search features and filters are available to help you sort through and make sense of your matches. If you choose, you can also reach out to your matches via the Ancestry messaging system to share information, ask questions, or collaborate on research.

Thrulines

Ancestry’s ThruLines tool expands on the common ancestor hints algorithm by searching other Ancestry trees for genealogy connections between your tree and the one posted by your DNA match. In cases where your tree or the genetic cousin’s tree is incomplete (no obvious shared ancestor), ThruLines aims to build out the missing connections based on data from other Ancestry member trees. The result is a tree illustrating possible genealogical paths that connect you and your match via a common shared ancestor. Since the connections are based on user-created trees, the connection is only as accurate as the trees that provide the data, and also may not represent all genealogical connections between you and your match. However, Thrulines can be invaluable as a starting point for figuring out how you and a match are related.

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  1. “Genetic Communities™ White Paper: Predicting fine-scale ancestral origins from the genetic sharing patterns among millions of individuals,” AncestryDNA (www.ancestry.com/cs/dna-help/communities/whitepaper : accessed 23 December 2020).


Photo credit: Ancestry®️

©2021 Kimberly Powell. Use of this article elsewhere without permission violates copyright. Short excerpts and links are welcome, with credit and a link back to Learn Genealogy.

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