A new day, a new thing

My goal to learn something new every day

Day 69: Cousins

Earlier today, during a chat with one of my students, she mentioned that she had around ‘ten nephews’. Given her age, around 21, and the fact that people born in the 90s in Korea tend to have just one sibling, I assumed she’d made a mistake. Not wanting to embarrass her (or myself) I double checked to see how many brothers or sisters she had. One—I was correct.

“Are you sure you mean nephews? Or do you mean cousins?” I asked. She thought about it for a brief moment before saying “no, it’s not cousin, it’s my father’s brother’s son’s son.”

“That’s still a cousin” I told her, “but we can call it a second cousin.” But no sooner had I said it than I started to doubt myself. “Is that really a second cousin?” I thought. It kind of sounds right, but I wouldn’t bet my house on it. And then I got to thinking about the different types of cousins: third, fourth, fifth and the like. And what about those removed ones? The whole issue of a removed cousin is something that has baffled me for years, ever since I was a kid in fact, ever since I saw this, which of course was at a time when you’d have been looked at as if you were mad for mentioning a Google (unless your looker-on was a mathematician).

First, second, third

The terms first cousin, second cousin and third cousin are used in a similar way as adding on the prefix great to grandparent. In fact the two terms actually have a connection. Your first cousin (although we don’t tend to say the ‘first’) is the child of one of your aunts or uncles. If you are first cousins, it means you share the same grandparents.

Your second cousin would be one of your grandparent’s brother/sister’s grandchild. Or perhaps an easier way to think about it is if you share the same great-grandparents, you are second cousins.

Third cousins are people who share the same great-great-grandparents, sixth cousins share the same great-great-great-great-great-grandparents and so it goes on. You are nth cousins, so long as you share the same number of greats when it comes to your grandparents.

But what if you have a common ancestor with person X, but you and person X are not the same number of generations away from that common ancestor? This is where the removed part comes in.


The word removed is used to describe a cousin who is not the same generation as you. Take for example, your grandfather’s brother’s son (not grandson), let’s call him ‘Bob’. You share a common ancestor—your great-grandfather. But to Bob, he is just his grandfather. So you and Bob are not from the same generation, you are one generation apart, which makes you first cousins once removed.

The number used before removed simply says how many generations there are between you and your cousin. The whole removed thing can get quite confusing though. Fortunately genealogists—the people who study family histories—have come up with relationship charts that help you to see the relationship between two people who share a common ancestor.

Relationship chart

Here is a relationship chart that I’ve put together.

Click to enlarge

Click to enlarge

How to use

To find the relationship between you and another person, you first need to make sure that you have a common ancestor. Then look at your relationship to the common ancestor, using the blue bar at the top of the chart. Next, look at the relationship of your relative to the common ancestor using the red bar down the left side of the chart. Where the two meet shows the relationship between you and the relative.

For most of the chart, you can actually use the red bar or blue bar first to find the relationship, because when it comes to talking about cousins, the relationship is mutual. However, if just one of you is the child of the common ancestor, then your relationship will be different depending on who’s closest to the common ancestor. I.e. you will either be an aunt/uncle or niece/nephew. If this is the case, the way to think about it is by saying you (blue bar) are [relationship] to relative (red bar).

This page here (pdf) has the more familiar family tree view of the relationship between relatives, as well as a relationship chart similar to the one I have made above. The family tree view is actually quite a bit easier to use for closer relationships.

And the student I mentioned at the beginning of this post? She was talking about her first cousins once removed. The common ancestor that they share is my student’s grandfather. But to the cousins she was referring to, that common ancestor is their great-grandfather.

2 comments on “Day 69: Cousins

  1. livinglearning
    March 11, 2015

    Your chart is really helpful. I remember trying to figure this out when my cousins were born. They’re my first cousin’s kids, which I guess makes them first cousins once removed. Maybe. Later I ended up having to decide that my mom’s cousins (who I met through Facebook) are also first cousins once removed, but in the other direction.


    • David Harbinson
      March 11, 2015

      I’m glad you found it useful, Anne. It’s still a little confusing when I think about it right now, but getting there. Today’s post is actually going to be an extension of this one because there’s a bit more I’ve found out this morning. Watch this space…

      Liked by 1 person

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This entry was posted on March 10, 2015 by in Family and tagged , , , , , .


March 2015

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