Discrepancies in Irish DNA Ancestry: An Exploration of Genetic and Historical Factors

When two DNA testing services provide different percentages of Irish ancestry, it can be perplexing. This article explores the reasons behind these discrepancies and how various factors, including reference populations, DNA matching, and regional variations, contribute to the differing results. Additionally, we will delve into why AncestryDNA and MyHeritage may offer varying estimates and how to interpret these results in the context of family history and genetics.

Factors Contributing to Discrepancies in Irish DNA Estimates

Reference Populations

Each DNA testing company uses different reference populations to determine ethnicity estimates. AncestryDNA and MyHeritage may have unique datasets and algorithms, leading to variations in the estimates. For example, AncestryDNA might use a dataset that includes more contemporary Irish populations, while MyHeritage might rely on a broader range of historical and regional data. This difference can result in differing percentages of Irish ancestry being reported.

DNA Matching and Algorithms

The methods used to analyze your DNA can also vary between companies. AncestryDNA might have a more conservative approach in identifying genetic markers associated with Irish ancestry, while MyHeritage could be more inclusive. These differing approaches can lead to variations in the estimated percentages of Irish heritage. It's important to consider the company's historical and regional focus when interpreting these results.

Regional Variations

Another factor that can influence the results is the definition of 'Irish' ancestry. Companies may define it based on specific regions and historical migrations. For instance, AncestryDNA might use more contemporary Irish populations, while MyHeritage might include a broader range of historical Celtic regions. This can result in different estimates as different populations and regions have varying levels of genetic overlap with the Irish.

Updates and Improvements

Companies like AncestryDNA and MyHeritage regularly update their algorithms and reference panels. This can lead to changes in the estimated percentages of Irish ancestry over time. If you tested at different times, the results might reflect these changes. These updates often incorporate new scientific findings and more comprehensive databases, providing a more accurate picture of your ancestry.

Genetic Overlap

Genetic overlap between neighboring regions and countries can complicate the results. For example, the genetic similarities between the Irish and other Celtic regions might lead to higher percentages of Irish ancestry being detected by one service compared to another. This overlap can make it challenging to determine the exact origin of certain genetic markers.

Anne's Case Study

Consider Anne's experience, where AncestryDNA reports 31% Irish ancestry while MyHeritage reports 82% Irish ancestry. This discrepancy can be explained by the factors mentioned above. For example, if AncestryDNA uses a more contemporary dataset that heavily emphasizes the past few centuries, it might result in a lower percentage of Irish ancestry. Conversely, if MyHeritage considers a broader range of historical and regional data, it might report a higher percentage of Irish ancestry.

Interpreting AncestryDNA Results

Ancestry is primarily focused on building family trees and is therefore more concerned with recent generations. Rich Ancestry reports 88% English ancestry, which is likely due to the fact that your ancestors lived in England and your cousin's neighbors lived there as well. However, many ancient population studies classify Germanic DNA as English DNA, due to the cultural changes during the migration era. This can lead to varying results depending on which DNA service you use. For instance, while your DNA may be exported to Celtic counties, it might be partially attributed to your own Celtic DNA.

The results from AncestryDNA can also vary depending on the timeframe of the testing. For example, you might see different levels of Irish, English, and Scandinavian ancestry depending on when you took the test. Additionally, you might see a mix of nationalities and regions, such as the Highlands, Argyll, Ulster, Dublin, Kilkenny, and Wales. The Anglo-Saxon ancestry could be represented by 12% in the results, and the Scandinavian influence could be distributed within Dublin and Ulster.

Key Takeaways

When you encounter differing results from different DNA testing services, it's important to consider the factors that contribute to these discrepancies. Reference populations, DNA matching and algorithms, regional variations, updates and improvements, and genetic overlap all play significant roles in the accuracy of your estimated ancestry. By understanding these factors, you can better interpret the results and build a more comprehensive understanding of your ancestry.