DNA tests can reveal important details regarding ancestry and ethnic origins. We explore how DNA and ethnicity are intertwined.
Many of the queries we receive at Legacy Tree Genealogists concern elusive ancestors who are difficult to trace. Sometimes there are rumors of descent from Native American, African, or Jewish ancestry. Other times there are no clues at all regarding an ancestor’s origins. In cases of ethnic origins, DNA testing is a unique tool that can assist in proving or disproving family stories, or revealing the origins of a “brick-wall” ancestor.
There are three types of DNA tests: Y-chromosome, mitochondrial, and autosomal. Each type of test can reveal important details regarding ancestry and ethnic origins depending on the different inheritance patterns associated with each of these three types of DNA. Here we will discuss Y-DNA and mitochondrial DNA tests, which are also known as direct-line tests.
The Y-chromosome is inherited along the direct paternal line of ancestry. Each male individual received their Y-DNA from their father, who inherited it from his father, and so on. In this way, the Y-chromosome is handed down in much the same way as surnames in Western cultures.
Mitochondrial DNA is inherited along the direct maternal line of ancestry. Each individual inherits their mitochondrial DNA from their mother, who inherited it from their mother, and so on.
When two individuals share a common Y-DNA signature, this means that they share a common direct-line paternal ancestor. When two individuals share a mitochondrial DNA signature in common, we know that they share a common direct-line maternal ancestor.
Y-DNA and mitochondrial DNA are passed on intact to descendants, but occasional mutations help to distinguish unique Y-DNA and mtDNA lineages from each other. Some of these unique lineages, called haplogroups, are specific to localities, ethnicities, and geographic areas.
For example, some specific signatures within mitochondrial haplogroups A, B, C, and D indicate Native American ancestry. Another signature in mitochondrial haplogroup B, known as the Malagasy motif, indicates that an individual has direct-line maternal ancestry from Madagascar. Some Y-chromosome signatures within haplogroup R are closely associated with Irish and Scottish ancestry. In one of the recent projects at Legacy Tree, we discovered that a client had a unique Y-DNA signature which is commonly associated with the descendants of Niall of the Nine Hostages, a 5th-century Irish king. Niall is a legendary and controversial figure, but regardless of the historicity of his life, we were able to conclude through Y-DNA analysis that the client likely had direct-line paternal ancestry in Scotland or Ireland where this signature is most commonly found. This was supported by the fact that his closest matches claimed origins in these areas.
There are unique Y-DNA and mtDNA signatures associated with African, Native American, East Asian, and Ashkenazi Jewish ancestry. Even if the haplogroup itself is not unique to a specific locality, comparison against close matches can sometimes help to identify the probable origin of the shared common ancestor.
Though both Y-DNA and mtDNA haplogroups use an alphabetic nomenclature, the designations have no relationship to one another. For example mitochondrial DNA haplogroup A, which is commonly found in East Asia and the Americas, does not coincide with the geographic distribution patterns of Y-DNA haplogroup A, which is indicative of direct-line paternal African ancestry.
Both Y-DNA and mtDNA are inherited along direct paternal and maternal lines. Therefore, if your ancestor of interest is not a direct-line paternal or maternal ancestor, it may be necessary to search for descendants who do descend along the direct line to test hypotheses regarding an ancestor’s origin.
It is also important to remember that haplogroups are representative of deep ancestry and can sometimes be anomalous within the context of modern and ancient migrations. For example, one study in 2007 found several members of a British family with documented genealogies back into the 1700s. Despite the fact that they had lived in Yorkshire for generations, their Y-DNA belonged to halplogroup A, which is typically indicative of African ancestry. Several researchers have attributed this unique lineage to the settlement of Africans and Romans of African descent during the Roman Era of Britain.
Currently, there are only two major genetic genealogy testing companies that offer information about mitochondrial DNA and Y-DNA: 23andMe and Family Tree DNA. As part of their $199 test, 23andMe offers information about the haplogroups or deep ancestry of the maternal and paternal lines. Family Tree DNA is the only genetic genealogy testing company that offers genealogically conclusive Y-DNA and mtDNA tests. They also offer several levels of testing (37, 67, or 111 marker Y-DNA tests and HVR1/HVR2 or full sequence mtDNA tests). Depending on the specific details of a project, the lower testing levels can be sufficient to investigate ethnic origins.
If you have an unknown ancestor or family stories of unique ethnicities, our researchers at Legacy Tree Genealogists would love to assist you in preparing a testing plan and interpreting your DNA test results. Contact us today to get started.
 Moore, L. T., McEvoy, B., Cape, E., Simms, K., & Bradley, D. G. (2006). A Y-Chromosome Signature of Hegemony in Gaelic Ireland. American Journal of Human Genetics, 78(2), 334–338.
 Turi E. King; Emma J. Parkin; Geoff Swinfield; Fulvio Cruciani; Rosaria Scozzari; Alexandra Rosa; Si-Keun Lim; Yali Xue; Chris Tyler-Smith & Mark A. Jobling (2007a). “Africans in Yorkshire? The deepest-rooting clade of the Y phylogeny within an English genealogy”. European Journal of Human Genetics 15 (3): 288–293