Neither AncestryDNA nor 23andMe is categorically more accurate than the other. Both companies use the same underlying technology (genotyping chips) and produce highly consistent results internally, with identical twins receiving matching ethnicity estimates 94.5% to 99.2% of the time from the same company. But when the same person’s DNA is run through both companies, agreement drops to somewhere between 52.7% and 84.1%. That gap isn’t because one test is broken. It reflects genuine differences in how each company builds its reference populations, groups geographic regions, and applies statistical algorithms to your raw data.
Why Results Differ Between Companies
Every ethnicity estimate is a comparison. The company takes your DNA and measures how similar it is to reference panels: curated groups of people with deep, documented roots in specific regions. AncestryDNA and 23andMe support a similar number of population groups, but AncestryDNA’s reference panel is roughly 50% larger in overall representation. A bigger reference panel can improve precision, but what matters just as much is how well those panels represent the specific populations relevant to your ancestry.
The two companies also draw regional boundaries differently. One might lump “Northwestern European” together where the other splits it into separate Scottish, Welsh, and English categories. These choices are somewhat arbitrary, and they’re the main reason your percentages look different across platforms. Neither set of numbers is wrong; they’re answering slightly different questions about the same DNA.
Database Size and Relative Matching
For many people, finding relatives matters as much as ethnicity percentages. Here, database size is the deciding factor. AncestryDNA is approaching 30 million DNA kits, making it the largest consumer DNA database in the world. 23andMe has dropped to just under 14 million total users, and only about 11.1 million of those participate in relative matching. Roughly 8.8 million have opted into segment matching through the chromosome browser, a tool that lets you compare specific stretches of DNA with your matches.
If your primary goal is connecting with biological relatives, discovering unknown family members, or building a family tree, Ancestry’s database gives you roughly twice the pool of potential matches. 23andMe’s chromosome browser, on the other hand, offers a more hands-on tool for people who want to analyze exactly which DNA segments they share with a match.
Parental Side Separation
AncestryDNA offers a feature called SideView that separates your ethnicity results into contributions from each parent, even if neither parent has taken a DNA test. It works by grouping your DNA matches into two clusters (one for each side of your family) and using those clusters to figure out which chunks of your genome came from which parent. Ancestry reports a 95% precision rate for this grouping for 90% of its customers, largely because of the sheer statistical power of its match network.
23andMe can also split results by parental side, but it works best when at least one parent has also been tested. Without a parent’s kit, the separation is less reliable. If seeing “Mom’s side: 40% Italian, Dad’s side: 55% German” matters to you, Ancestry currently has the edge for users testing alone.
Where Each Company Performs Better
23andMe tends to pick up small trace ancestries that AncestryDNA’s algorithm smooths out. If you have, say, 2% of something unexpected in your background, 23andMe is more likely to report it, while Ancestry may fold it into a broader regional category or drop it below a confidence threshold. For people with complex, multi-ethnic backgrounds, that granularity can feel more informative.
Ancestry, meanwhile, offers “Genetic Communities” (or “Communities”), which pinpoint not just a country but a specific migration pattern or settlement group your ancestors belonged to. Users frequently report these communities as strikingly accurate, sometimes identifying the exact county or historical migration their family followed. 23andMe has a similar feature with “Recent Ancestor Locations,” but it relies partly on user-reported data from other customers rather than the algorithm-driven approach Ancestry uses.
Health Reports
23andMe is FDA-authorized to provide certain health and carrier status reports, covering predispositions for conditions and carrier status for genetic variants you could pass to children. Ancestry does not offer health reports. If genetic health screening is part of your motivation, 23andMe is the only option of the two. Keep in mind that consumer health reports screen for a limited number of variants and are not a substitute for clinical genetic testing ordered through a healthcare provider.
Privacy and Security
23andMe holds certifications under three international security standards: ISO/IEC 27001 for information security management, ISO/IEC 27701 for privacy management, and ISO/IEC 27018 for protecting personal data in cloud environments. These certifications are audited annually by an independent third party. Ancestry also maintains security protections but has not publicized equivalent third-party certifications to the same degree.
Both companies have faced scrutiny over data handling. 23andMe disclosed a significant data breach in late 2023, and its financial instability has raised concerns about what happens to customer data if the company is sold. Ancestry, as part of the larger Blackstone-owned family of companies, has a more stable corporate footing but stores data in a similarly centralized way. Regardless of which test you choose, both companies allow you to download your raw data and then delete your account and stored DNA information.
Which Test Should You Choose
Your best choice depends on what you’re trying to learn. For building a family tree and finding biological relatives, Ancestry’s database is twice as large and its community features are strong. For health predisposition reports, 23andMe is the only option. For ethnicity breakdowns, both are similarly reliable at the broad level, but 23andMe captures more trace ancestry while Ancestry provides more specific migration communities.
Many experienced genealogists test with both. The raw DNA data from either company can be uploaded to third-party tools like GEDmatch or FamilyTreeDNA for additional matching and analysis, often for free or a small fee. If you can only pick one, match your choice to your primary goal rather than chasing a single “most accurate” answer, because accuracy in consumer DNA testing depends more on what you’re measuring than on which company measures it.