Over the last decade, DNA testing has transformed family history research. Millions of people around the world have taken a DNA test in the hope of discovering their ancestry, finding unknown relatives or learning more about their ethnic origins. While these tests can provide remarkable insights, they are often misunderstood. Many people receive their results and are unsure what they are actually looking at or how to use the information to progress their family tree.
At Welsh Family History, we regularly work with clients who have taken a DNA test but need help interpreting the results. DNA is an incredibly powerful research tool, but it works best when combined with traditional genealogical research using historical records, parish registers, census returns and wills.
So what does a DNA test actually tell you? Consumer tests analyse hundreds of thousands of markers across your genome and compare them with millions of other people in the company’s database. The results generally fall into three categories:
The first is Ethnicity where tests will estimate where your ancestors may have originated over the past several hundred years. They are calculated by comparing your DNA with reference populations from around the world.
It’s important to remember that these are estimates, not definitive facts. As testing companies update their databases and improve their algorithms, your ethnicity percentages can change over time.
For those with Welsh ancestry, it is common to see a mixture of Wales, England, Scotland and Ireland due to centuries of migration and shared genetic heritage.
Secondly the DNA test will give you a list of genetic matches. These are people who share segments of DNA with you because you have a common ancestor. Matches can range from close relatives such as siblings or first cousins to distant cousins who share an ancestor several centuries ago.
The amount of shared DNA is measured in centimorgans (cM). Generally speaking:
- Around 3,400 cM suggests a parent or child.
- Around 2,500 cM suggests a full sibling.
- Around 850 cM may indicate a first cousin.
- Between 40 and 200 cM often represents second to fourth cousins.
- Below 20 cM usually indicates a much more distant relationship.
While these figures provide useful guidance, multiple relationships can share similar amounts of DNA, so documentary evidence is always essential.
The final element of the test results will look at genetic communities or regions where your ancestors are likely to have lived in recent centuries. These communities are often far more useful than ethnicity estimates because they reflect recent migration patterns and family connections.
For Welsh researchers, these communities can often point towards particular counties or regions where further documentary research should begin.
One of the biggest misconceptions is that DNA testing replaces family history research. In reality, it complements it. DNA can identify potential relatives, but it cannot tell you exactly how everyone is related. That requires careful analysis of birth, marriage and death records, census returns, parish registers, probate records, newspapers and other historical sources.
For example, you may share 120 cM with someone. DNA confirms that you are related, but determining whether you share great-grandparents, great-great-grandparents or another relationship altogether requires building both family trees and comparing them carefully. This combination of genetic evidence and documentary research produces the strongest conclusions.
Many first-time testers are disappointed when they don’t immediately discover exciting family secrets. In reality, most DNA results confirm what traditional research has already suggested. Others focus heavily on ethnicity percentages, even though these are the least precise part of the results.
The real value lies in your DNA matches. Even relatively distant cousins can provide photographs, family stories, certificates and information that help solve longstanding mysteries.
One of the greatest strengths of DNA testing is its ability to help solve family history mysteries that cannot be answered through traditional records alone. It has proved invaluable in identifying unknown parents, biological grandparents, previously unknown siblings, adoption cases and families separated through emigration. DNA evidence can also reveal connections between branches of a family that documentary sources alone may never uncover. However, these discoveries rarely come from a single DNA match. Instead, they usually require the careful analysis of multiple matches, shared DNA, family trees and historical records to build a reliable picture of how individuals are connected.
If you are considering taking a DNA test, there are several companies to choose from, each offering different advantages. Some have significantly larger databases, increasing your chances of finding relatives, while others provide more advanced tools for analysing DNA matches. For those researching Welsh ancestry, a testing company with a large international customer base can be particularly beneficial, as it increases the likelihood of connecting with descendants of Welsh emigrants now living in countries such as the United States, Canada, Australia and New Zealand. Many experienced researchers also choose to upload their DNA results to other compatible databases, where permitted, to maximise the number of potential matches.
Receiving your DNA results is only the beginning of the journey. While ethnicity estimates often attract the most attention, experienced genealogists focus on the information that can actually help solve family history questions. This includes the amount of DNA shared with each match, groups of shared matches, family trees attached to those matches, geographical patterns and migration routes, all supported by traditional documentary research. By combining these different sources of evidence, it is often possible to identify common ancestors and solve long-standing brick walls that would otherwise remain unanswered.
At Welsh Family History, we combine DNA analysis with traditional genealogical research to help our clients make sense of their results and uncover the stories behind their family connections. Whether you have recently received your DNA results or have spent years trying to understand hundreds of unexplained matches, we can help you interpret the evidence, identify common ancestors and integrate your findings into a well-researched family tree. If you would like expert assistance with your DNA results, please get in touch to discuss how we can help.
