DNA Comparison

Categories: DNA

Here are some tips for getting started with DNA comparisons and moving toward DNA confirmation with the ideal of setting each parent-child relationship in your tree as "Confirmed with DNA".

Contents

How to Find Test-Takers

One of the core purposes of WikiTree's DNA features, including the Ancestor Confirmation Aid, is to help you figure out who could take a DNA test in order to confirm or reject a certain relationship. To make a comparison, of course, you need two or more people to take comparable tests. How do you find them?

Ask about tests

When trying to confirm your ancestors, the first thing to do is to make sure that your cousins haven't taken DNA tests that they just haven't entered on WikiTree.

You may want to e-mail all the active WikiTree members on a DNA Descendants page simply to ask if they have taken a test. If they have, score! If they haven't, it might start a conversation about why they might want to and how to choose one. You can point them to https://www.wikitree.com/wiki/DNA_Tests

Choosing test-takers

How do you know who should be tested?

WikiTree has a tool to make finding these potential test-takers easy: The DNA Descendants page.

Let's say you want to figure out whether A's father is really B. The potential test-takers will be the living people on the DNA Descendants page for the earliest-known ancestor (EKA) in the direct paternal line of A. To get to this page, simply go to A's DNA Ancestors page, find the last person listed in the Y-chromosome line, and then click the icon to see that EKA's DNA Descendants.

The more distant cousin relationship that two test-takers have, the more generations they could potentially confirm. If two brothers take tests, they could only confirm that they have the same father. If cousins (sons of brothers) take tests, they could confirm their fathers and their grandfather. Second cousins can confirm their great-grandfather, etc.

Warning: If you plan to spend money on a new test trying to confirm a specific paternal or maternal ancestor, be sure that the ancestor is more recent than (or is) the most-recent common ancestor (MRCA) in the direct paternal or maternal lines of the test-takers. As noted above, two brothers taking tests can't confirm their grandfather. Two first cousins taking tests can't confirm their great-grandfather, etc.

Another warning: Although it may seem preferable to always test more distant cousins, as opposed to closer cousins, there is a risk. The more distant they are, the more chance they won't confirm any generations at all. If test-takers don't match, all we can say for certain is that there is some non-paternal event (illegitimacy) or error in the genealogy on WikiTree. We can't say where it is. See the section below on tests that don't match.

Entering tests on WikiTree

If a relative has taken a test but hasn't entered it on WikiTree yet, ask them to click the "DNA Test Information" link under the "Add" menu in the upper-right corner of any page.

If you have access to their test results you can enter it for them. Be careful to enter it as a test of their DNA, not as a test of your DNA. Click the DNA link from their profile.

If there are no testable descendants

In many cases, there are no living people on an ancestor's DNA Descendants page who can be tested.

This means we need to return to conventional genealogy. If you can break through the brick wall of your earliest known ancestor (EKA), many new cousins will be discovered.

Maybe you could add the "collateral" relatives in your tree — such as the brothers of your paternal ancestors. And their sons. And their sons. Every connection opens up more possibilities. Moreover, because WikiTree works as cousin bait, every profile you create increases the chances that a distant cousin will find one of the profiles and start adding and connecting to it. Connections tend to snowball.


What to Do When Tests Match

Celebrate! See DNA Confirmation.


What to Do When Tests Do Not Match as Expected

If two yDNA or mtDNA tests appear on an ACA and a person's profile, but the test results don't match each other, it means there is one or more "non-paternal event" (illegitimacy) or genealogical error in a test-taker's tree.

Removing relationships on WikiTree

It's important that non-matching tests don't appear on an DNA Ancestor Confirmation Aid (ACA) and an ancestor's profile indefinitely.

They remain there for as long as the incorrect relationship(s) that connected them remain on WikiTree. That is, we don't edit DNA test connections directly. We edit WikiTree relationships. Test connections are automatically rebuilt at night based on those relationships.

It might seem easier just to remove the tests. However, it's part of our community ethos that we are all striving for an accurate single family tree. Wiki Genealogists want to remove inaccurate relationships from WikiTree. DNA testing is a powerful tool for identifying these inaccuracies.

That's certainly easier said than done. How do you identify which relationship is incorrect? How do you go about finding the non-paternal event or genealogical error?

Look for obvious problems in deep ancestry

Since there's a chance for an error in every generation, the deeper in history you go, the more likely it is that there will be one or more mistakes.

The most common source of incorrect yDNA and mtDNA test connections on WikiTree is spurious connections in deep ancestry. WikiTree does not place a limit on the number of generations we connect for tests, up or down. We follow the paternal/maternal line all the way up to the last ancestor, and then we follow all the direct paternal/maternal lines down from that ancestor.

Click to the DNA Ancestors page of each test-taker and click to the profiles of the very deepest ancestors. You might spot a parent-child relationship with sources that are clearly questionable. You can then remove the relationship and only link the two profiles in their biographies.

Finding a third test-taker

If a genealogical error isn't easy to find, you might consider finding a third test-taker. Although this can be expensive, if you explain the exciting possibility of definitively confirming or rejecting their ancestry, perhaps they can be enticed. :-)

See the section above on finding test-takers.



This page was last modified 09:46, 7 April 2017. This page has been accessed 432 times.