Understanding Ancestry DNA Results Divergence: Why My 23andMe Results Differ from

Have you ever noticed that your 23andMe ancestry results mention 20% French and German, but your results don't show this? This discrepancy arises from the fact that different DNA testing companies use different reference panels and approaches to analyze your genetic makeup. Let's delve into why these differences occur and what implications they have for your genetic ancestry.

The Differences in Ancestry DNA Reports

The divergent results between 23andMe and are not indicative of a mistake, but rather a reflection of the unique methods each company employs. 23andMe and , like other direct-to-consumer (DTC) DNA testing companies, generate ethnicity reports based on comparing up to 0.1% of your autosomal DNA (atDNA) to a collection of groups known as reference panels or reference populations. These reference populations are a combination of industry data and other customers of the same testing company.

These differences can be attributed to several factors:

Individual Data Selection: The reference populations used by 23andMe and may include different sets of individuals. If your French and German cousins have contributed genetic samples to 23andMe but not to , the 23andMe report is likely to show higher percentages of these ancestries. Different Reference Panels: DTC companies continuously update their reference populations due to new data and improvements in technology. This means that the results you receive today may be different from those you received in the past, and there is no guarantee that they will remain the same for all individuals tested. Marker Selection: Each company may choose to analyze different regions of your DNA, which can result in different conclusions about your ancestry. For instance, 23andMe and might focus on different base pairs within the 0.1% of DNA they analyze.

Comparing Results Across Testing Companies

Comparing the results from different DTC DNA testing companies can be enlightening yet challenging. Here are some key considerations:

Sample Size and Reference Populations: The accuracy and reliability of ethnicity reports depend on the size and diversity of the reference populations used. Larger and more diverse reference populations tend to yield more accurate results. Methodology: The specific methods used by each company to analyze and interpret DNA can significantly impact the results. This includes the types of markers analyzed and the algorithms used to interpret the data. Temporal Changes: Results can change over time due to updates in the reference populations, new data, and improvements in analysis techniques. This means that your DNA test results today may not be the same as they were yesterday or last year.

Implications of Divergent Results

While divergent results from different DNA testing companies can be confusing, they do not necessarily negate the value of your ethnicity report. Here are a few implications to consider:

Complementary Information: Divergent results can provide a broader picture of your genetic heritage. For instance, a higher percentage of French and German ancestry in 23andMe might be supplemented by other significant ancestries reported by Verification: Comparing results from different companies can help verify the accuracy of your ancestry information. If the same ancestry group is consistently reported across multiple testing companies, it increases the likelihood of its validity. Personal Precision: While the results may differ, they still offer valuable insights into your genetic background. It's essential to consider the precision of the analysis and the significance of the reported percentages.

Conclusion

In conclusion, the discrepancies between 23andMe and results are normal and expected given the nature of DTC DNA testing. These differences are the result of differences in reference panels, marker selection, and temporal changes. By understanding these factors, you can better interpret your ancestry DNA results and use them to piece together the complex tapestry of your genetic heritage.