Family history research can feel overwhelming, especially when you consider the hundreds of ancestors in your family tree. Many genealogists simplify their approach by focusing only on their direct line – parents, grandparents, great-grandparents, and so on. While this strategy seems logical, it actually limits your research effectiveness and can lead to incomplete or inaccurate family histories. Expanding your research to include siblings, cousins, and other relatives – known as collateral research – transforms your genealogy work in powerful ways.
This post was originally published in November 2021 and last updated on 6 July 2025
Reason 1 – More Sources Means Better Accuracy and Error Detection
All sources can contain errors – even original sources and official documents. The most frequent causes of errors are when the informant provides incorrect information or does not have sufficient information, or when the person recording the information mishears or misunderstands the information provided.
Limiting your research to your direct line means you are using fewer sources. You need sufficient sources to corroborate information, identify and resolve inconsistencies. If you do not use enough sources, you are less likely to notice errors. You will also have less information and evidence to develop accurate conclusions.
Reason 2 – Fill Information Gaps Through Collateral Research
Sources are often incomplete and lacking some information. The more sources you look at, the greater the chance of filling the gaps.
Sources about people related to your direct line, such as siblings and cousins, may contain additional information. Researching them is referred to as FFANs research – Family, Friends, Associates and Neighbours.
Read my article about Broadening your research with FFANs.
Reason 3 – Interesting Relatives Reveal Family Stories
Let’s face it, some people are more interesting or famous than others. These ones tend to have more written about them and the information provided can shed light on the whole family, not just the individual concerned.
Reason 4 – DNA Analysis Requires Extended Family Context
If you are using DNA evidence in your research, then researching your extended family is essential. Using DNA evidence effectively is fundamentally dependent upon researching the relationships between people in the extended family.
Read my articles about using DNA in family history.
Reason 5 – Connect with Fellow Researchers and Shared Resources
When you research your extended family you are more likely to identify and perhaps communicate with other people researching that family. They may be able to assist with your research, have information that you do not and perhaps even family photographs you have never seen before.
Take Action: Expand Your Research Today
Successful family history research requires looking beyond your direct ancestors to include the full family network. When you research siblings, cousins, and extended relatives, you create a comprehensive picture that strengthens every aspect of your research. You’ll catch more errors, fill gaps, uncover fascinating stories, make essential DNA connections, and build relationships with fellow researchers.
It does require additional investment of time and effort, but your research will benefit. Start small and gradually extend your family history context.
Ready to take your genealogy skills to the next level? Learn more proven research strategies in my book, The Good Genealogist, where I share the methods that create accurate, comprehensive family histories.
About the Author
Danielle Lautrec is a genealogy educator, researcher, and author of The Good Genealogist. With qualifications in history, family history, and historical archaeology, she teaches for the Society of Australian Genealogists.
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