Genealogy 101: Who Is My First Cousin Once Removed?

Introduction: In this article – part of an ongoing “Introduction to Genealogy” series – Gena Philibert-Ortega explains a potentially confusing family relationship, cousins: first, second, removed, etc. Gena is a genealogist and author of the book “From the Family Kitchen.”

One day my cousin came over for a visit with his two young sons. He introduced me as “Aunt Gena.”

However, I’m not their aunt – because their father is my first cousin (to be more precise, he is my mother’s sister’s son) and not my brother. Because I’m a genealogist, of course, I had to correct him. He explained that he said I was their aunt because I was older than they were. However, that’s not how relationships work. Anyone who was born before their own aunt or uncle can attest to that.

I corrected him and explained that his sons and I were “first cousins once removed.”

He then gave me a questioning, perplexed look and asked: “What does ‘removed’ mean?”

Illustration: a chart illustrating the different types of cousins, including genetic kinship marked within boxes in red which shows the actual genetic degree of relationship (gene share) with “self” in percentage (%)
Illustration: a chart illustrating the different types of cousins, including genetic kinship marked within boxes in red which shows the actual genetic degree of relationship (gene share) with “self” in percentage (%). Credit: Gringer; Wikimedia Commons.

Family Relationships

Historically, family relationships have been confusing. It’s not unusual to find that an ancestor referred to someone as a cousin when they really weren’t. Just think about your own life. Do you ever refer to a good friend as a “sister” or a “brother”? I’ve had friends’ children refer to me as their “aunt” because they felt like I was “family.” Familial relationships are just plain confusing, even when correctly identified.

An Oxford Dictionaries blog post titled “What is a second cousin?” points out that “English is sometimes irritatingly vague when it comes to kinship terminology, even within fairly close family relationships. I can’t tell (without more context) if your brother-in-law is your sister’s husband or your husband’s brother.”* Another example: referring to someone as your “aunt” could mean your father’s or mother’s sister. You can see how English lets us down in describing those we are related to!

For family historians who work on connecting generations through parental-child relationships, identifying relationships correctly is important. Especially in today’s world when your DNA results provide you with relationship estimates that include cousins.

When attempting to figure out a familial relationship ask yourself: “Who is the most recent common ancestor?” This will help you determine your relationship to another person. So, for example, siblings share parents, and cousins (the children of siblings) share a common set of grandparents.


Now, about that term “cousin.” What is a cousin? As mentioned above, they are the children of siblings, or the child of one’s aunt or uncle. It’s probably important to think of a first cousin as someone you share a set of grandparents with. That goes back to the idea of who is the most common recent ancestor.

As an example, my son and my brother’s son are cousins and they share a common set of grandparents (my and my brother’s parents).


Now, let’s mix things up a bit. If my son were to have a girl, what would that child’s relationship be to my son’s first cousin – who is my brother’s son?

Well, the relationship of that newest addition (my granddaughter) to my brother’s son (my nephew) would be a first cousin once removed. Why? Because compared to my nephew, my granddaughter would be an additional generation removed from the common ancestor. Meaning that there is a generation separating these two people: my parents are the grandparents to my nephew but the great-grandparents to my son’s child.

So, what about this term “removed?” What in the world does that mean? It has to do with what generation they are from the common ancestor. Now, make sure you don’t equate the word “generation” with “age.” And don’t assume because someone is not your “first cousin” that they are automatically your “second cousin.”

Which leads me to the question: Who is your second cousin? Once again, we look at who the common ancestor is. Second cousins share a pair of great-grandparents. If my son and my nephew had children, those children would be each other’s second cousins.

Figuring It Out

You can find several different types of relationship charts online, including this one from GenealogyInTime Magazine, which help make it easier to determine your relationship between two people. If you are using a genealogy software program, most include a relationship calculator that can also help.

When analyzing your DNA results you may need to go beyond the relationship estimates provided by your testing company. Consider using the Genetic Genealogist’s Shared cM Project Tool.

* “What is a second cousin? and other cousin questions ,” Oxford Dictionaries ( accessed 21 January 2018).

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