If you’ve ever been curious about your family tree, you’ve probably encountered the term “third cousin once removed.” But what does that mean? In short, it means the relationship between any two people who share great-great-grandparents as their most recent common ancestors. Let’s explore this concept in more detail.
Defining Third Cousins Once Removed
A third cousin once removed is a person who is related to you by sharing a set of great-great-grandparents—but by different generations. For instance, if your grandparent and your grandparent’s first cousin were siblings, then your grandparent’s first cousin would be considered your third cousin once removed. This is because you both share the same set of great-great-grandparents (your grandparents’ parents) but you are separated by one generation (your grandparents).
Using another example, if your great-aunt and her first cousin had children, then those children would also be considered your third cousins once removed because they would share the same set of great-great-grandparents (your great aunt’s parents) but would be separated by two generations (your great aunt and her first cousin).
The Relationship Tree
Understanding how third cousins once removed fit into family trees can help make sense of these relationships. The simplest way to explain it is to draw a chart or diagram of your family tree and mark the spot where each relative fits in relation to one another.
For example, if Person A is related to Person B through their shared grandparents (one generation away), then Person A and Person B are second cousins. But if Person A is related to Person C through their shared great-grandparents (two generations away), then Person A and Person C are second cousins once removed. And if Person A is related to Person D through their shared great-great-grandparents (three generations away), then they are third cousins once removed from one another.
Conclusion:
Understanding how relatives fit into each other’s family tree can be tricky at times—especially when it comes to determining relationships with more distant relatives like third cousins once removed. It helps to think of these relationships in terms of generations; the greater number of generations that separate two people will determine just how far apart they are on the family tree, making them either closer or more distant relatives such as second or third cousins respectively. Being able to understand this relationship between different family members can help us better appreciate our extended families and all the unique bonds we share with them!
FAQ
What is a third cousin once removed?
A third cousin once removed is a relative who shares the same set of great-great-grandparents as you, but who is one generation away from you on the family tree. This means that, while you and your third cousin once removed share many of the same family members, you are separated from each other by one generation.
One way to determine whether or not you and another person are related as third cousins once removed is to draw out your family tree and locate the spot where each person’s family line intersects with that of the other person. If you find that the two of you share the same set of great-great-grandparents, then it is likely that you are related as third cousins once removed.
Do I establish a relationship with a third cousin once removed?
There is no formal way to establish a relationship with a third cousin once removed, as this relationship is typically considered to be very distant. However, you may find that the two of you have similar interests or share connections through mutual friends and family members, which can help to strengthen the bond between you. Additionally, it can be helpful to stay in touch with distant relatives like third cousins once removed to help preserve your family history and keep you connected to your roots.

Throughout his career, Andras has developed a deep understanding of DNA and its applications in genealogy and genetic testing. He has helped thousands of individuals uncover their ancestral heritage, using cutting-edge DNA analysis to trace family lineages and reveal connections across generations.