Types Of DNA For Genealogy

Four kinds of DNA for Genetic Genealogy

Four different kinds of DNA are available for genealogists. Each type is useful in specific situations, but not all are relevant or useful for everyone. The only type of DNA test available at all the major DNA vendors is autosomal testing. When most people say they’re “testing their DNA” for genealogy, they are referring to taking an autosomal DNA test, like the MyHeritage DNA test, although they may not realize that’s the type of test they are taking. Most DNA testing companies simply refer to the name of their test, but they are all autosomal tests – just branded differently and with different capabilities provided by each company. A second type of genealogical DNA test is Y-DNA for patrilineal lineage testing and matching. Only males have Y chromosomes, and therefore only males can take a Y-DNA test for matching on their direct paternal line. A third type of test is mitochondrial DNA for both males and females. Mitochondrial DNA tests your mother’s direct matrilineal line – a direct line of mothers.

Some vendors include high-level Y-DNA and mitochondrial DNA haplogroups with their autosomal tests, but not detailed haplogroups, matching or other tools. For that, you need to take that specific kind of test. Let’s look at all three types of DNA tests and what they offer.

Autosomal DNA

Autosomal DNA, the DNA on chromosomes 1-22 is inherited from both parents. Each child receives half of their parent’s autosomal DNA, but may inherit different amounts of their earlier ancestors’ DNA due to random recombination over the generations. Autosomal testing revolves around matching other testers and identifying your common ancestors to confirm your genealogy and break down brick walls. People searching for unknown parents, grandparents and siblings make use of autosomal DNA testing.

Testers can always count on matching their second cousins or closer and will match many of their third and more distant cousins. MyHeritage's newwest tool, the cM Explainer provides estimates of how you and your matches may be related, including the age of testers, if known. Shared DNA matches, surnames and locations between matches and groups of people are important clues to identify their common ancestors.

Additionally, MyHeritage includes advanced tools for their MyHeritage DNA testers such as AutoClusters, providing cluster-based organization and a colorful visualization of how your matches also match each other, facilitating the identification of common ancestors. Each colored cluster will share an ancestral line. Another tool, Triangulation, automatically identifies shared matching segments and confirms ancestral connections by using the chromosome browser at MyHeritage.

MyHeritage places brackets around portions of segments where all people being compared match the tester and each other. Theory of Family Relativity is a tool that provides pathways to connect you and your DNA matches to common ancestors using both trees and supporting documents from MyHeritage’s extensive data collection.

Ethnicity estimates identify geographic regions where you match the residents more closely than other locations, suggesting that you have an ancestral connection to that region. The corresponding tool, Genetic Groups, reflects groups of people that you match either within or outside of your ethnic regions, suggesting more recently shared common ancestors. Genetic Groups might reflect immigrants who may have moved as a community to a new location outside their original ethnic region, such as settlement within the United States.

X-DNA

X-DNA, another type of autosomal DNA, is part of the sex selection process and is passed on the 23rd chromosome.

• Males inherit a Y chromosome from their father, which makes them male. Males only inherit an X chromosome from their mother.
• Females inherit two X chromosomes, one from each parent, but no Y chromosome.

Therefore, the X chromosome conveys a unique inheritance pattern since a male’s X chromosome is never recombined with an X chromosome from his father, but a female’s X chromosome is recombined between both parents, just like chromosomes 1-22.  

For genealogy, this means that the X chromosome can be particularly enlightening if utilized correctly.

Males, shown in blue, only inherit their X chromosome from their mother, who inherited a copy of her X chromosome from all of her pink and blue ancestors.

Females inherit an X chromosome from both parents, but their male ancestors only inherit their X chromosome from their mothers. This unique inheritance path, as shown above, can immediately eliminate many common ancestors in testers’ and their matches’ trees. However, not all DNA testing companies include X matching in their results. Both 23andMe and FamilyTreeDNA provide X matching, but all major companies do provide the X chromosome results in the DNA download file.

Y-DNA

Y-DNA is passed intact from father to son on the twenty-third chromosome and is what makes males, male. Y-DNA is never mixed or recombined with the DNA of the mother. In Western culture, the Y-DNA inheritance path is also the surname path, so Mr. Jones would probably expect to have Y-DNA matches with other men of the Jones surname. Y-DNA tests can be purchased at different levels from FamilyTreeDNA. The higher the level tested, and matching, the more information can be revealed about the common Y-line ancestor, and when they lived.

Male adoptees or men seeking the identity of their paternal ancestors, including a father or grandfather, can take a Y-DNA test to obtain matches and narrow their focus. Y-DNA is often utilized in conjunction with autosomal testing. In addition to matching, and because it is not mixed with the DNA of the mother, Y-DNA is passed nearly intact generation after generation, except for occasional minor mutations. Therefore, Y-DNA can be tracked far back in time to the original ancestor of all living men today. Major lineages have been named with letter-based clan names called haplogroups, like R-M269, which is similar to a genetic clan. Much more specific haplogroup names which can identify locations are assigned with advanced Big-Y testing. Y-DNA is important to identify patrilineal ancestors along with the source of the male lineage and tracks those ancestors through time. On the other side, females do not have a Y chromosome, and instead inherit an X chromosome from their father as well as their mother.

Mitochondrial DNA

Mitochondrial DNA is passed intact from mothers to all of their children but is only passed on to the next generation by females. Mitochondrial DNA is not admixed or recombined with the DNA of the father and is a separate molecule, not carried on the twenty-third chromosome. In the human body, mitochondrial DNA is responsible for the generation of energy. Of course, genealogists use it for identifying and confirming ancestors.

Typically, in western culture, female’s surnames change in every generation when they marry. Because of this disconnect, women’s surnames are often lost to history. Unlike Y-DNA, mitochondrial DNA does not follow a direct surname path and instead follows a person’s mother’s mother’s mother’s direct maternal lineage. After the surname is no longer known, the mitochondrial DNA continues to match and provide invaluable hints.  

Mitochondrial DNA can be tracked to the earliest female ancestor of all people living today. Like Y-DNA, mitochondrial DNA is also assigned haplogroups. The full sequence test (mtFull) at FamilyTreeDNA is the most detailed test available and includes matching, mapping and haplogroup identification.

DNA Tests and answers for everyone

Different DNA testing companies provide different types of DNA tests and tools. yHeritage focuses on providing best-of-class autosomal DNA tools for genetic genealogists, including Shared Matches, Common Locations and Surnames, AutoClusters, a Chromosome Browser, Triangulation, Theories of Family Relativity, cM Explainer, Ethnicity and Genetic Groups.

References

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