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What is genetic ancestry testing?
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Dtcgenetictesting

What is genetic ancestry testing?

Genetic ancestry testing analyzes single nucleotide polymorphisms (SNPs) to provide clues about familial relationships and where a person’s ancestors might have lived, using Y‑chromosome, mitochondrial, and autosomal DNA analyses.

Overview

Genetic ancestry testing is one way people can learn about their family history. Ancestry testing uses common DNA variations called single nucleotide polymorphisms (SNPs) to provide clues about relationships between families and where a person’s ancestors might have lived. Established geographical groups and individuals who are related to one another tend to share more of these common DNA variations.

Types of genetic ancestry testing

Y chromosome testing

This type of testing analyzes genetic variations on the Y chromosome, one of the sex chromosomes. The Y chromosome is present in males, who have one X chromosome and one Y chromosome, while females have two X chromosomes. As a result, Y chromosome testing can only be performed on males. Since the Y chromosome is passed from father to son, variations in the Y chromosome can be used to explore ancestry in the direct male line.

Mitochondrial DNA testing

are structures within cells that convert the energy from food into a form of energy that cells can use. Although most DNA is packaged into chromosomes within the nucleus of the cell, mitochondria have a small amount of their own DNA, known as mitochondrial DNA. Mitochondrial DNA testing analyzes genetic variations in this type of DNA. Both males and females have mitochondrial DNA, so mitochondrial DNA testing can be performed on anyone. However, only egg cells provide mitochondria to the developing embryo. So only females pass mitochondrial DNA to their children. As a result, mitochondrial DNA testing only provides information about the female ancestral line.

Autosomal DNA testing

In humans, each cell typically contains Twenty-two of these pairs (chromosomes 1-22) are called autosomes, and they look the same in males and females. The X and Y chromosomes make up the 23rd pair. (Males have one x and one Y chromosome. Females have two X chromosomes.) The autosomes contain the DNA that are needed for most of the body's functions. The X and Y chromosomes are the sex chromosomes are involved in sex determination and development. Autosomal DNA testing evaluates large numbers of SNPs in the autosomes. Autosomal DNA testing provides a more comprehensive analysis of an individual’s genetic ancestral information than either Y chromosome testing or mitochondrial DNA testing, which only represent single ancestral lines.

During autosomal DNA testing, an individual’s pattern of SNPs is compared to testing (reference) databases that contain SNP information from people whose ancestry is already known. After SNP patterns are analyzed, a report is generated with predictions about the most likely locations of a person’s ancestors.

Limitations of genetic ancestry testing

  • Different reference databases are used across genetic testing companies 
  • Populations are not represented equally in all reference databases 
  • Tests generally do not account for historical population migration 

Several reference databases are available for use in genetic ancestry testing. Because the specific reference databases and the methods used for analyzing individual samples can vary across genetic testing companies, ancestry estimates may not be consistent from one company to another. Additionally, different populations may not be equally represented within a given reference database, so the results for some populations may be less informative than for others. Even within a given reference database, information about a population will change over time as more genetic information is added to the database.

Human migration patterns can also complicate the interpretation of genetic ancestry test results. Most human populations have migrated many times throughout their history. Because of this movement, genetic ancestry test results may reflect where a person’s family originated and not where they lived. The fact that populations may have mixed with nearby groups as they moved around may also cause ancestry estimates to differ from an individual’s expectations.

Interpretation and sharing of results

Many genetic ancestry testing companies provide online forums and other services that allow people to share and discuss their test results with others. Sharing results with others can lead to unexpected findings about existing relationships and reveal relationships that were previously unknown.

It is important to remember that the information provided by genetic ancestry testing is just one part of a person’s story. These tests typically analyze only a portion of a person’s genetic information, and the tests do not consider the environmental factors, such as social relationships and cultural experiences, that are also important in shaping someone’s sense of identity.

Additional resources

  • The National Human Genome Research Institute (NHGRI): Human Origins and Ancestry.
  • The National Institute of Standards and Technology (NIST): How do Companies Measure DNA to Discover Your Ancestry?
  • The Tech Interactive: How do ancestry tests work?

Related topics in the Direct‑to‑Consumer Genetic Testing chapter

  • What is direct-to-consumer genetic testing?
  • What kinds of direct-to-consumer genetic tests are available?
  • What is genetic ancestry testing?
  • What are the pros and cons of direct-to-consumer genetic testing?
  • What do the results of direct-to-consumer genetic testing mean?
  • What does it mean to have Neanderthal DNA or Denisovan DNA?
  • What should I know before proceeding with direct-to-consumer genetic testing?

Frequently Asked Questions

utosomal DNA testing analyzes the 22 pairs of non-sex chromosomes and is the only type that can identify relatives from both your maternal and paternal sides, including cousins, aunts, and uncles. Y-chromosome and mitochondrial DNA testing are uniparental, meaning they only trace one specific line (paternal for Y, maternal for mitochondrial). Autosomal testing is generally more useful for finding living relatives and building a family tree, while uniparental tests are better for tracing deep ancestral migration patterns.
The accuracy of ancestry testing decreases significantly as you go further back in time. Autosomal DNA is reliable for tracing ancestors within the last 5 to 7 generations (roughly 100 to 200 years). Beyond this point, recombination events shuffle DNA segments, making it difficult to pinpoint specific ethnic groups. Y-chromosome and mitochondrial DNA can trace lineages much further back, potentially thousands of years, but they only represent a single line of descent rather than your entire family tree.
No, genetic ancestry testing cannot definitively prove descent from a specific named individual unless there is a verified DNA sample from that person or their direct descendants in a database. While you may see matches with people who claim such lineage, this is circumstantial evidence. Without a direct DNA match to a verified descendant, any claim of royal or historical descent remains speculative and is not scientifically confirmed by the test results alone.
Y-chromosome testing is exclusive to males because it traces the direct paternal line passed from father to son. It cannot provide information about your maternal line or female relatives. To explore your maternal ancestry, you would need mitochondrial DNA testing, which is passed from mother to all children but only transmitted by daughters to the next generation. For a broader view of both sides of your family tree, autosomal DNA testing is the most effective method as it analyzes DNA from all ancestors.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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