A family tree test is a genealogical DNA test that analyzes your autosomal DNA to estimate your ethnic origins and identify genetic relatives, helping you build or verify your family tree. These tests, offered by companies like AncestryDNA, 23andMe, and FamilyTreeDNA, compare hundreds of thousands of genetic markers across your genome to reference populations and other customers.
What a Family Tree Test Actually Measures
Most consumer DNA tests use autosomal DNA, which you inherit from both parents. Autosomal DNA is found in your 22 pairs of non-sex chromosomes, and it recombines each generation, so you receive roughly 50% from each parent. This allows the test to see about 5 to 6 generations back with reasonable accuracy, though estimates become less precise beyond that.
Two other types of DNA are also analyzed, depending on the company and the test you order:
- Mitochondrial DNA (mtDNA): Passed from mother to child, unchanged except for rare mutations. It traces your direct maternal line (mother’s mother’s mother, etc.).
- Y-chromosome DNA (Y-DNA): Passed from father to son, tracing your direct paternal line. Only males have a Y chromosome, so only men can take this test for their paternal line; women can ask a father or brother to test instead.
AncestryDNA and 23andMe focus on autosomal DNA, while FamilyTreeDNA offers separate mtDNA and Y-DNA tests for deeper lineage tracing. Some tests, like 23andMe, also include health-related genetic risk reports, but these are optional and separate from the family tree features.
How the Test Works Step by Step
The process is straightforward, but understanding each step helps you interpret results correctly.
- Order and collect: You receive a saliva collection kit. You spit into a tube or swab your cheek, then mail it to the lab. No blood draw is needed.
- DNA extraction and genotyping: The lab extracts DNA from your cells and uses a microarray chip to read hundreds of thousands of specific single nucleotide polymorphisms (SNPs) – locations where people commonly differ.
- Comparison to reference panels: Your SNPs are compared to reference populations from different world regions. These panels are built from people with known ancestry from those regions.
- Ethnicity estimate: The algorithm calculates what percentage of your DNA matches each reference population. For example, you might see 45% British & Irish, 30% French & German, and 25% Nigerian.
- Relative matching: Your DNA is compared to other customers in the company’s database. Shared DNA segments indicate a common ancestor. The size and number of shared segments estimate how closely related you are.
- Results delivered: You get an online dashboard with your ethnicity percentages, a list of DNA relatives, and sometimes a chromosome browser showing which parts of your DNA you share with a relative.
How to Choose a Family Tree Test
No single test is “best” for everyone. Your choice depends on your goals and geographic location.
- For the largest relative database: AncestryDNA has the biggest customer database, so you’re more likely to find matches. It also integrates with an extensive family tree builder.
- For health and ancestry combined: 23andMe offers both ancestry and health reports, including carrier status and polygenic risk scores. Its relative matching is smaller than Ancestry’s but still substantial.
- For deep paternal or maternal lineage: FamilyTreeDNA specializes in Y-DNA and mtDNA tests. If you want to trace a specific surname line or ancient migration, this is the best choice.
- For international users: MyHeritage DNA is popular in Europe and has a growing database, plus tools for photo colorization and record matching.
Consider whether you want raw DNA data download (all major companies allow it), privacy controls, and whether the company has been sold or changed its terms, as this affects how your data is used.
Common Problems and Limitations
Family tree tests are powerful but not infallible. Here are the most frequent issues people encounter:
- Ethnicity estimates change: Companies update their reference panels and algorithms, so your percentages can shift without your DNA changing. A 2019 study found that 23andMe and AncestryDNA gave different results for the same person, though broad regions were similar.
- Adoptees and unknown parentage: If you are adopted or have an unknown parent, a DNA test can reveal close relatives, but it may also uncover unexpected family situations. Many companies offer genetic counseling resources.
- Endogamy: If your ancestors came from a small, isolated population (e.g., Ashkenazi Jewish, French Canadian, or island communities), DNA segments are shared more broadly, making it harder to tell close from distant relatives.
- False paternity: A test can reveal that your legal father is not your biological father. This is a significant emotional event; be prepared before testing.
- Privacy risks: Your DNA data can be used by law enforcement in some cases. In 2018, police used a public genealogy database to identify the Golden State Killer, raising concerns about consent.
Costs and What You Get
Prices vary by company and promotions, but typical costs as of 2024:
- AncestryDNA: $99 for ancestry only, $119 with a family tree subscription.
- 23andMe: $99 for ancestry, $199 for ancestry + health.
- FamilyTreeDNA: $79 for autosomal, $119 for Y-DNA, $159 for mtDNA, with combos available.
- MyHeritage: $79 for ancestry, $99 with a subscription.
Most companies run sales around holidays. The price includes the kit, lab analysis, and lifetime access to your results. You can download your raw DNA data for free, but third-party analysis tools like GEDmatch are free to use. Some companies charge a monthly subscription for advanced family tree features, but basic tree building is usually free.
Privacy and Data Safety
Before you spit in a tube, understand how your data is handled. All major companies let you delete your DNA sample and account, but they may keep your data for research unless you opt out. Read the consent forms carefully.
- Opt-in research: Most companies ask separately if you want your data used for research. You can say no without affecting your results.
- Law enforcement access: Ancestry and 23andMe have stated they fight law enforcement requests, but FamilyTreeDNA has cooperated with the FBI. If this concerns you, choose a company with a strict privacy policy.
- Third-party sharing: Your data may be shared with partners for research, but not sold to insurance companies in the US due to GINA (Genetic Information Nondiscrimination Act), which prohibits health insurers from using genetic info. However, life, disability, and long-term care insurance are not covered by GINA.
Always use a strong password and enable two-factor authentication on your DNA account, as your genetic data is sensitive.
Alternatives to DNA Testing
If you are not ready for a DNA test or want to supplement it, traditional genealogy research is a valuable alternative.
- Family records: Interview older relatives, collect birth/marriage/death certificates, and look for family Bibles or photo albums.
- Online databases: Free sites like FamilySearch and WikiTree, or subscription sites like Ancestry and MyHeritage, have billions of historical records.
- Local archives: Courthouses, churches, and libraries often have original records not digitized.
- Genetic genealogy without testing: You can upload existing DNA data from one company to another (e.g., Ancestry to GEDmatch) for free, expanding your matches without a new test.
DNA tests are most useful when combined with paper records. A test can point you to a possible ancestor, but documents confirm the relationship.
Frequently Asked Questions
How accurate are family tree DNA tests?
Ethnicity estimates are accurate at the continental level (e.g., European vs. African) but become less precise for specific countries. Relative matching is highly accurate for close relatives (parents, siblings, first cousins) and reasonably accurate for second to third cousins, but false matches can occur at the distant cousin level.
Can a DNA test tell me my exact family tree?
No. A DNA test gives you a list of genetic relatives and ethnicity percentages, but it does not draw your family tree. You must use the matches and records to build the tree yourself. Some companies offer tools to help, but they are not automatic.
Will a family tree test work for adopted people?
Yes, and it is often very effective. Adoptees can find biological parents, siblings, and other relatives by matching with close DNA relatives. However, results can be emotionally complex, and many companies provide support resources or you can work with a search angel (a volunteer who helps adoptees).
Do I need to test both my parents to get useful results?
No, but testing a parent helps “phase” your DNA, meaning you can see which segments come from which side. This makes ethnicity estimates more accurate and helps you sort matches. If a parent is unavailable, testing a sibling or grandparent can also help.
Can I upload my DNA data from one company to another?
Yes, many companies allow free uploads of raw DNA data from other companies. For example, you can upload an AncestryDNA file to MyHeritage or FamilyTreeDNA for free, though some advanced features may require a fee. This expands your match database without buying another test.
How far back can a family tree DNA test trace ancestry?
Autosomal DNA is useful for about 5-6 generations (roughly 150-200 years), but becomes unreliable beyond that. Y-DNA and mtDNA can trace a single line back thousands of years, but they only cover your direct paternal or maternal line, not your whole tree.
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