Identical Twins Receive Wildly Different Results From DNA Testing Companies
A new investigation reveals that major DNA testing companies provide inconsistent ancestry results for identical twins. Experts warn that users should treat these genetic analysis reports as rough estimates rather than absolute facts.
A recent investigation by CBC's Marketplace reveals significant flaws in commercial DNA testing by showing that identical twins receive completely different ancestry results. The twins submitted their DNA to five major companies, including 23andMe and AncestryDNA, and fail to receive matching results from a single service. Yale researchers verify that the twins' DNA is statistically identical, proving that the discrepancies stem entirely from the testing companies themselves.
Each DNA testing company relies on its own proprietary algorithms and reference databases to analyze genetic data, leading to highly varied conclusions. For example, FamilyTreeDNA attributes 14 percent of the twins' DNA to the Middle East, while the other four companies do not. The results from 23andMe show even stranger inconsistencies, giving one twin nearly 10 percent less broadly European ancestry and assigning them French and German heritage that the other twin apparently lacks.
These dramatic differences highlight the lack of aggressive regulatory oversight in the direct-to-consumer genetic testing industry. 23andMe admits that its analyses are merely statistical estimates, but customers rarely realize just how approximate these reports actually are. While this twin experiment lacks the rigorous sample size of a formal scientific study, it effectively reminds consumers to take mail-order DNA analysis with a healthy grain of salt.