Using your DNA results

Privacy Level: Public (Green)
Date: 31 Jul 2019
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You can use DNA to validate and extend your tree, and you don't need a detailed scientific understanding of DNA to do it. Your DNA match information is much more useful than the ethnicity estimates that disappoint some people, and it can be quite gratifying to find evidence that the family tree you have created is accurate. On this page I've tried to list resources that might be useful for people who want to get started analyzing their own DNA results.

Most of this page is intended to help those who have taken DNA tests and are trying to understand them. For those who have not yet tested, WikiTree provides advice on types of tests and testing companies at Help:DNA Tests.

Questions and suggestions welcome.

WikiTree and DNA

Unlike other genealogy websites, WikiTree allows users to display their DNA test information on their ancestors' profiles for several generations back, and provides a process with specific criteria for documenting DNA Confirmation.

What this does: It enables WikiTreers who share common ancestors to find each other, to learn whether descendants of their ancestors have tested, and to understand the DNA evidence behind connections found on the common family tree. See Help:DNA Features for more information.

What this doesn't do: It does not prove that you match someone, even if you are both listed on the same ancestor's profile. You have to investigate each match for yourself. Even if you do share DNA with someone listed on your ancestor's profile, that alone does not prove that the DNA is from that ancestor. (Are your trees well documented? Are the other people that match you both consistent with the identified family line? Is the match strength reasonable for the identified relationship?)

How to enter your information: You do not upload actual DNA data to WikiTree. You simply state what tests you have taken. To do that, go to your own profile. Click on the "DNA tested" link on the left side of the gray area near the top of your profile. Scroll down to "Add New Test Information" and select from the drop-down menu. Save when you're done.

WikiTree will connect your autosomal test information to all your blood relatives out to eight degrees of separation—up to sixth great grandparents and out to third cousins. Y-DNA and mtDNA information will be connected to all relatives who might share the DNA with you. DNA information is updated once a day, so you will need to wait a day after posting your test information before it shows up on your ancestors' and relatives' profiles. (Obviously, for this to work, your ancestors and relatives must have profiles on WikiTree, and you must be connected to your family.)

DNA Confirmation. WikiTree policy requires that when relationships are marked as "Confirmed with DNA," DNA confirmation statements must be added to the profiles. See Help:Confirmed with DNA and Help:Triangulation among other WikiTree Help pages.

Using your DNA results

Identifying your matches

Once you get your test results, you will need to identify your matches in order to make use of the information. Some you may already know, such as first cousins, but those are the exceptions. Identifying your matches generally depends on your having traced your family tree back at least a few generations (those seeking to identify unknown parents are a special case). The Blaine Bettinger blog post listed just below has many good tips for identifying matches.
In early 2019, Ancestry introduced its ThruLines, which illustrate possible relationships between DNA matches descended from common ancestors up to fifth great grandparents. These can be helpful in identifying matches, and suggesting common ancestors, but their accuracy depends on the accuracy of user trees*. Make sure you've verified the paper trail before relying on ThruLine information. (See Randy Seaver's May 3, 2021 blog post, listed in "Resources" below, for an example of an erroneous ThruLine.)
*Ancestry's ThruLines are derived from all user trees, and may not represent what you or your matches have on your own trees.

Tips for identifying matches

Organizing your match information

Here's what I've done. This section is adapted from one of my own G2G posts. No one has to do things my way, of course, but I feel very strongly that a list of matches, even the identified ones, must be organized into a coherent set of records if it is to be maximally useful.
Start with Ancestry*, particularly if you are a subscriber so you can take full advantage of the information that may be connected to your matches. Analyze your matches one by one beginning with the strongest. Start a list, grouping your matches by most recent common ancestors, when you know them, or family group if you don't know the MRCAs (the family group will be determined by shared matches, and some groups can be more specifically identified than others). One way to get started is the Leeds Method (see the resource list below). In the beginning, the matches without trees will go into the family groups, but you may be able to do more with them later.
*Obviously, this comment only applies to those who have tested with Ancestry. I recommend Ancestry as the first test for most people, due to their large user base, option for downloading raw DNA, and pretty-good user tools (except for the lack of chromosome detail).
Also set up a chart of your ancestors (i.e. a tree or a fan chart) and check off which ones are validated by DNA.
Then, if you have the time and ambition, start a set of chromosome maps (see below).
Meanwhile, build out your tree by tracing the descendants of the siblings of your own direct ancestors, starting with the more recent and working back.
As you get oriented, you should be able to see which of your ancestors are questionable (not validated by DNA) as well as where you have large groups of mysterious matches. Those are the ones I would pursue. There are various ways to try and identify your matches (see above), including contacting them.
And after you've done all that, and depending on what you want to spend, for the difficult ancestral lines you could try some targeted DNA testing.

Taking a closer look

Chromosome detail

The weaker the match, the more uncertain it is. It helps to have chromosome detail, which some testers provide, but which Ancestry does not. In order to get the chromosome detail for Ancestry matches, you can ask the matches to upload their DNA raw data to Upload instructions are included on the website. (It will be necessary to sign up for the free GEDmatch account in order to view the instructions. Log in first, then use the link.) You will also find some educational links on the GEDmatch home page. Here are a couple others:

Cluster analysis offers automated cluster analysis. What this does is group DNA matches by shared DNA and presents the information in a visual format. See this example. Each colored square is one person, and the colored groups are people who share common ancestors.
Unfortunately, since 2020 Ancestry has refused to cooperate with Genetic Affairs, but data from other DNA test providers can still be analyzed (I think). GEDmatch also offers cluster analysis as a Tier 1 service ($10 per month).


Helpful G2G discussions

Using DNA

  • DNA Triangulation February 4, 2020: More than the title suggests; several people discuss how they analyze their matches; one person links to his free-space page describing how he attempted to break down a brick wall.
  • Version 4.0 of the Shared cM Project is now available March 27, 2020: Links to Blaine Bettinger's blog post announcing his update; Edison Williams explains the usefulness of the shared cM numbers as well as some of the limits to our understanding of genealogical DNA. (See also list of Estes posts above.)
  • 52 Ancestors Week 25: Earliest June 18, 2019: SJ Baty explains how he used a combination of autosomal and Y-DNA to confirm his descent from an early ancestor (scroll down to SJ's answer, which includes the bold heading "Henry is the 21th great grandfather of SJ").




Chromosome mapping

Chromosome mapping identifies your DNA by the ancestor it came from. It is a powerful aid in identifying your DNA matches (which is useful for confirming, and possibly extending, your family tree). One approach is to map your chromosomes back to your four grandparents using simple yes/no choices for each separate paternal or maternal segment. Later, you can try and go further back.

As you might expect, it is necessary to have chromosome detail in order to do chromosome mapping. Some DNA testing companies provide it. The largest, Ancestry, does not. In order to obtain chromosome detail of your Ancestry DNA data, you can upload to, a free DNA matching website. Instructions on uploading are included on their website. GEDmatch is also useful for comparing DNA results of people who have tested with different companies.

Other DNA testing companies also offer the opportunity to upload Ancestry (and other) DNA data, and can provide chromosome detail. Roberta Estes provides instructions here.

At least two approaches to chromosome mapping that don't involve software or enormous spreadsheets can be found on-line: 1. Blaine Bettinger's visual phasing (see Resources list). It depends on having a sibling who is DNA-tested, preferably two. 2. Jim Bartlett's triangulation groups.

My chromosome maps are created using a modified version of Blaine Bettinger's Visual Phasing. See my personal map which I have posted to my WikiTree profile for the use of my matches. (Note: What I have posted is a summary; the detail comprises one map for each chromosome where my DNA is compared to my siblings' and our matches.)

The website also provides some mapping options. (I confess to not having kept up well with their newer features; the site is definitely worth exploring once you have mastered a few basic concepts.)

Resources for chromosome mapping

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  • Private Messages: Contact the Profile Managers privately: George Kelts and Lynn Kelts. (Best when privacy is an issue.)
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  • Public Q&A: These will appear above and in the Genealogist-to-Genealogist (G2G) Forum. (Best for anything directed to the wider genealogy community.)

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