Not too long ago, someone asked me what a collateral relative was. Simply put, a collateral relative is a family member who is not your direct ancestor or descendant.
A collateral relative could be Aunts and Uncles, Nieces and Nephews, Cousins, or siblings of your grandparents. In-laws of your ancestors, as well as step-siblings, step-children, other spouses, and any adopted family, might also be considered collateral relatives.
Why Should I Research Collateral Relatives?
You may not have inherited DNA from them, but collateral relatives can still prove immensely helpful in researching your ancestors. Indeed, their records can be substitutes when your ancestors’ documents are missing or incomplete.
For example, let's say your ancestor’s vital records don’t give the name of his/her parents. However, his/her sibling's birth certificate (which was likely created at a different time and may hold different details) could reveal the parents’ names.
Tips for Collateral Research
Seek out records of your collateral kin with the same urgency as you would for your ancestors. As previously stated, they may even contain details that are directly relevant to your ancestor. Start with your ancestors’ siblings, then work out to more distant relatives like cousins.
Document the whole family - Some sources document whole families, in which collateral relatives appear in the same record as your ancestors: censuses, obituaries, and more. So it may just take one extra step to record a collateral relative’s entry in addition to your ancestor’s. You can log details about a couple and all of their children using a family group sheet.
Collaborate
Lean on cousins, DNA matches, and other relatives in your extended family. You never know what family treasures are hidden in someone else’s attic.
Remember genealogy best practices
The fundamentals of good research apply to any historical person that you’re studying—ancestors or not:
Work backward in time
Document your findings
Consult a wide variety of records
Cite your sources
Avoid making hasty assumptions
Collateral relatives have the potential to break down your genealogical brick walls. With sound research methods and that broader pool of family members, you’ll set yourself up for success.