Using genetic genealogy, or genetic ancestry testing, people interested in family history (genealogy) can go beyond what can be discovered from relatives and historical documents. These tests have grown rapidly in popularity and provide an opportunity to reconnect people with their close and distant relatives. These records can be especially useful for adoptees and descendants of forced migrants who do not know their genealogical ancestry.

Testing for genetic ancestry involves comparing a large number of DNA variants measured in an individual with the frequencies of these variants being referenced to that of populations collected from around the world. People with certain backgrounds often share certain patterns of genetic variation. Generally, the closer two individuals, families, or populations are, the more variations they tend to share.

There are three types of genetic ancestry testing are commonly used for genealogy; Y chromosome, Mitochondrial DNA, and Single nucleotide polymorphism testing.

Through a Y chromosome test, ancestry in the direct male line can be discovered using variations in the Y chromosome, which is passed exclusively from father to son. As females do not possess a Y chromosome, Y chromosome testing is only performed on males. Women may, however, can ask a male relative to perform this type of genetic testing for them.

The mitochondrial DNA test looks for any DNA variations in the mitochondria. DNA is packaged mostly in chromosomes in the nucleus of a cell, but small quantities of DNA are also present in the mitochondria of cells (known as mitochondrial DNA). This type of testing can be used by either gender since mitochondrial DNA is inherited from their mothers giving insight into the direct female ancestral line.

The single nucleotide polymorphism (SNP) test compares the variations of single nucleotide polymorphisms within a person’s genome. The results are compared with those of others who have taken the tests to produce an estimate of a person’s ethnic ancestry. SNPs may indicate that, for example, a person’s ancestry is approximately 50% African, 25% European, 20% Asian, and 5% unknown. Genealogists utilize this type of test since Y chromosome and mitochondrial DNA test results, which only indicate specific ancestral lines, do not capture an individual’s overall ethnic origin.

However, genetic ancestry tests do come with limitations. Because test providers compare individuals’ test results to different databases of past tests, you must keep in mind that ethnicity estimations may change from one provider to the next.

Anyone wishing to know more about their ethnic roots, past connections, or contemporary relatives has a range of at-home DNA kits to choose from. Otherwise, most businesses offer online forums and other services that allow people who have been tested to share and discuss their results with others.

References:

https://en.x-mol.com/paper/article/1228438181883432960

https://medlineplus.gov/genetics/understanding/dtcgenetictesting/ancestrytesting/