Help:DNA Test Connections

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Over 30% of the profiles on our shared tree now have DNA test connections! Here is what they mean.


What is a DNA Test Connection?

A DNA test connection is a notice on a WikiTree profile that someone has taken a DNA test which might be helpful for confirming or rejecting relationships to that person (see an example).

Essentially, a test connection is an opportunity to try to scientifically prove or disprove what's been established through traditional genealogy.

This is something that can only be done on a single family tree where we all collaborate on the same ancestor profiles. Our system is unique to WikiTree and:

  1. helps genealogists discover and confirm their ancestors, and
  2. helps WikiTree's mission to grow an accurate single family tree.

Test connections include paternal or maternal haplogroups[1] along with GEDmatch IDs with easy comparison links and other useful information.

What Profiles Get Connected to Your Test?

  • Y-Chromosome: If a male on WikiTree has taken a Y-chromosome DNA test we go all the way up the direct paternal line, father-to-father, to find the test-taker's earliest-known paternal grandfather. Then, starting with this earliest-known paternal grandfather, we go down all the direct male lines, not just the test-taker's own line. The system includes all sons and skips all daughters and profiles without a specified Sex at Birth.
  • Mitochondrial: If a male or female on WikiTree has taken a mitochondrial DNA test we will go up the direct maternal line, mother-to-mother, to find the test-takers's earliest-known maternal grandmother. We then include all the children, male and female, of this earliest-known direct-line maternal grandmother. Then we take the daughters gathered in the previous step and add all her children, male and female. We repeat this down through all the generations. In every generation, all children are included, but only the children of daughters are included in the next generation. This is the same as what you see on the earliest-known maternal grandmother's DNA Descendants page in the mitochondrial section.

Percentages of Shared DNA

Autosomal DNA test connections include average expected percentages of shared DNA between the profiled person and the test-taker. You will see these percentage numbers on any profile with autosomal connections [example].

Any number you see below 50% is only an average based on relationships and patterns of inheritance.

We inherit exactly 50% of our autosomal DNA from our mother and 50% from our father. We get one set of chromosomes from each of our biological parents. But beyond our parents, the inheritance is random.

Since each one of our parents also inherited exactly 50% of their autosomal DNA from each of their parents we can estimate that we will have inherited about 25% of our DNA from each one of our grandparents. We don't know the actual percentage we inherit from our grandparents because the DNA we inherit for our parents is a randomly shuffled mixture of the DNA they inherited from their parents.

For more on this topic, see the Autosomal DNA statistics page on the International Society of Genetic Genealogy Wiki, and our discussion in G2G.

X-chromosome percentages

If the test-taker is expected to match the profiled person on the X chromosome, an X percentage is included after the autosomal percentage.

The X percentages are significantly less reliable than the autosomal percentages. For more information, see X Chromosome Recombination's Impact on DNA Genealogy by Jared Smith.

Connections for Surnames

You can see all the people on WikiTree with a given last name who have DNA test connections. This can be very helpful for surname studies.

For example, see Adams DNA Connections. Enter your own surname in the search form on that page.

Allow 24 Hours for New Connections

To get the test connection process started all you have to do is say that you have taken a DNA test. WikiTree does the rest.

The connections are made automatically, but not instantly. It may take up to 24 hours for tests to connect. It also takes up to 24 hours for test connections to be removed when family relationships are changed.

  1. In the future, we hope to automatically alert members when haplogroups that should match conflict. Automatic detection of haplogroup conflict will be difficult for the foreseeable future because of the inconsistent naming of haplogroups and changing of haplogroup labels through time. This would require more technical sophistication in the programs and/or users. In the meantime, if a haplotype comparison chart exists on the Web then it can be linked from the note field. For example, see Peter Roberts' Family Tree DNA yDNA test page.
  2. The testing company is likely to give you matches who are beyond third cousins. However, those cousins can't be reliably expected to share significant segments of your DNA. No autosomal test can definitively confirm or rule out a family relationship, but it would be unusual for second or third cousins to not share significant segments.

This page was last modified 20:42, 30 August 2023. This page has been accessed 217,473 times.