Understanding Your AncestryDNA Matches

Your AncestryDNA results are in. Maybe you’ve always been interested in genealogy, or perhaps you received the test as a gift, and really have no idea what to expect. There is a learning curve to understand DNA test results, even for seasoned genealogists.

AncestryDNA’s test is an autosomal DNA test, which looks at chromosomes 1-22 and the X-chromosome and provides information about many relationships and ancestors from both paternal and maternal ancestral lines. This post focuses on AncestryDNA’s results, but several other companies which offer autosomal DNA testing, including MyHeritage, 23andMe, and Family Tree DNA, provide similar features.

Autosomal DNA results include ethnicity predictions, as well as a “match list” – a listing of other testers, or genetic cousins, with whom you share DNA. While the ethnicity prediction is the feature that prompts many people to test, the cousin matching features contain significant information about your biological family and their origins, and can provide much more information for genealogical research once you know how to navigate the results.

Getting Started

“What do I do with these results?  I don’t recognize any of the names on my match list.”

This is a common sentiment upon first viewing one’s match list, and it can be disconcerting to not immediately see expected surnames. Before you start formulating “switched at birth” theories, take a few moments to learn about how to interpret these results.

Your main AncestryDNA page will look something like this. Click on the green “View All DNA Matches” button to view your match list.

If you have matches with predicted relationships closer than a 2^nd cousin whose names you don’t recognize, you may have uncovered a surprise. Even then, don’t be too quick to judge, because your Close Family match with “surferdood456” may turn out to be Uncle Henry, who hasn’t mentioned his new hobby.

Identifying Relationship Possibilities

Your genetic cousin matches are listed from closest to most distant. Each company has a different algorithm for classification, but typically matches are sorted from highest to lowest number of centimorgans shared. Centimorgans (cM) are the unit of measurement used to describe the amount of DNA shared between two people. The more you share with a match, the more likely you are to be closely related. For each match on your match list, the total number of cM is given, along with a predicted relationship.

AncestryDNA has 7 different groups for predicted relationships: Parent/Child, Immediate Family (full siblings), Close Family (half siblings, grandparent/grandchild, aunt/uncle/niece/nephew), 1^st cousin, 2^nd cousin, 3^rd cousin, 4^th cousin, Distant Cousin.

The number of centimorgans shared with any given genetic cousin is now displayed on the main match page. Previously this information was found by clicking on that person’s username, and then on the lower case “i” in the Predicted Relationship section.

The relationship “buckets” from the testing companies are broad and don’t specify all of the possibilities, such as half or “once removed” relationships. The number of centimorgans shared is more informative than the predicted relationship from the testing company; however, the number itself is not enough to determine a specific relationship. For nearly all relationships, there are other relationships that have the same expected amount of DNA shared. A 1^st cousin relationship has the same expected amount of DNA shared as a half aunt, or a great-grandparent.

Once the number of centimorgans shared between two individuals is known, many resources are available to suggest possible relationships. One resource that we particularly like is the DNA Painter Shared cM Project 3.0 tool v4.[1] This tool is a collaborative effort that combines user-submitted data with statistical probabilities. Many DNA relationship charts show cM ranges for various relationships, but there is always overlap between the ranges. This tool gives the probability of each relationship group.

For our 165 cM example above, the Shared cM Project probability tool shows that Half 2^nd cousin or its equivalents (2^nd cousin once removed, Half 1^st cousin twice removed, 1^st cousin three times removed) are the most likely options, although 2^nd cousin or equivalent is a definite possibility. Other options below are less likely, but still in the realm of possibility.

Use of Family Trees to Narrow Relationship Possibilities

Many new DNA testers will find that their matches are all 2^nd cousins or more distant. Most of us are not acquainted with the majority of our 2^nd, 3^rd, or 4^th cousins, so it’s typical to not recognize the names. Ancestry.com is well known for its large collection of family trees, and many AncestryDNA users have family trees that they have associated with their DNA results. These trees greatly simplify the process of understanding who a genetic cousin is, and how you are related to them. An Ancestry.com subscription is required to view other users’ family trees; however, you will be able to view ‘Common Ancestors' listed even without a subscription if you upload your family tree.

The following examples are the top seven matches from my match list. These matches have a variety of family tree options, including large and small family trees, unattached family trees, private trees, and no tree. The right side of the match list (next to the green “View Match” button) shows family tree information for each user.

Public Family Trees

Match #1 and I share 263 cM. Clicking on either his username or the green “View Match” button shows more information about him. His family tree shows that his mother was my dad's 1^st cousin. We share great-grandparents, so the amount of DNA shared and the 2^nd cousin designation make perfect sense.

Match #2 bears my maternal grandmother’s maiden name, and sure enough, his tree shows his great-grandparents, who are my great-great-grandparents, meaning a 2^nd cousin once removed between us, and the 209 cM shared is consistent with that relationship. Likewise, Match #4 is the only name originally recognized – a known 3^rd cousin with a large family tree.

Unattached Family Trees

The main match list page shows no family tree for Match #5, but clicking through to her page reveals a dropdown box containing a family tree:

The family trees for Matches #1, 2 and 4 were linked to their DNA results. Match #5 has not performed that step, and her tree is what is known as an unattached family tree. Caution is required with unattached family trees, as the tree may not include the tester, but many times they do, and may contain valuable information. In this case, the tree was informative, and showed that Match #5 is a 1^st cousin of Match #2.

Match #3 had a small unattached tree which only listed herself and the name of her deceased husband.  We’ll get back to her in a few paragraphs …

Private Family Trees

When the match page shows the number of people in a family tree followed by a padlock, the user’s family tree is private, and as such, no information is viewable by other users. Some users will grant access to their tree if you ask politely, but oftentimes, the private trees are still searchable. A blue “Search Matches” box appears at the top of the match list. Clicking on that box will display surname and location filters which can be used for searching. Match #7's test was administered by another person, so the only information initially available about her was her initials. A search for my maiden name included Match #7 in the list of results. Further searching of other known names in that family line helped me determine the identity of Match #7.

Shared Matches

Of course, many of the users with a “No family tree” designation actually have no family tree. This was true of Match #6. The Shared Matches feature was key to understanding how both Match #6 and Match #3 were related to me.

The Shared Matches feature is located near the top of the screen when viewing details about an individual match, in a black box in three parts (Pedigree and Surnames, Shared Matches, and Map and Locations). The headings for these boxes are Surnames, Matches, and Locations on Ancestry’s mobile app. Pedigree and Surnames is the default, and will always display initially.

Clicking on Shared Matches will display a new match list, containing genetic cousins who share DNA with the tester and the currently viewed match. Most of the time, when three people share DNA with each other, the three all have a common ancestor. Occasionally the relationships between the three parties will involve three different sets of ancestors, so caution should be utilized in analyzing these results. This situation is rare but should be kept in mind.

Shared Matches functionality can be used to categorize one’s test results into groups. Tracking those groups deserves its own post, but typical strategies include use of the Notes functionality on a user’s match page, word processing or spreadsheet software, or even handwritten notes.

The list of shared matches for Match #6 contained Match #2 and Match #5, who already were identified as relatives of my maternal grandmother. This branch of the family was from Minnesota, which has excellent online birth, marriage, and death records available. Match #6 has an unusual surname, so marriage records involving her first name and surname were searched, resulting in a handful of candidates. These candidates were researched, and one of them was the daughter of my grandmother’s 1^st cousin.

Using These Techniques for Unknown Family

Our discussion thus far has assumed some knowledge of one’s biological family, but the same tools and techniques are used in search for unknown family, whether that be unknown parents, grandparents, or more distant ancestors. Family trees for groups of shared matches can be studied to find common surnames and ancestral couples.

Match #3 shares DNA with a large group of testers who are known descendants of one of my sets of great-great-grandparents. Investigation of Match #3’s small unattached tree showed no connection to the expected family. Contact with Match #3 revealed that she was a late-discovery adoptee, with limited information about her biological mother and no information about her biological father. The techniques discussed in this post, along with extensive family tree building, were used to identify Match #3’s biological parents.

Contact with Other Users

Other AncestryDNA users may be contacted by clicking on the match’s username, and then pressing the green “Send Message” near the top right of the match’s page. (Some users have disabled this feature, in which case no green button is displayed). We recommend keeping initial contact short, while sharing only those details that are pertinent. If the identity of the genetic cousin is a complete mystery, asking them to share names of their great-grandparents is often a good approach.

Studying one’s AncestryDNA results can yield a wealth of information and clues about one’s family. We recommend initial focus on the closest matches with family trees, followed by use of Shared Matches functionality to group matches by line of descent. Understanding the ancestral connections to your genetic cousin matches may take a bit of time, but is a worthwhile pursuit to help further your genealogical research.

Legacy Tree Genealogists is not affiliated with any of the companies mentioned in this blog post. However, our resident DNA experts would be happy to help you analyze and make sense of the results you get from any of them. Contact us and let us know how we can help you.

[1]“The Shared cM Project 3.0 tool v4,” DNA Painter, https://dnapainter.com/tools/sharedcmv4, accessed August 2018.