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What Is a 'Second Cousin, Once Removed'? Let Us Explain

What Is a 'Second Cousin, Once Removed'? Let Us Explain
Credit: Karin Hildebrand Lau - Shutterstock

Want to be the most popular person at your next family gathering? Be the person who can explain the difference between “second cousins, once removed” and “third cousins, twice removed” and your relatives will look on you like you’re a genius, an oracle, an armchair genealogist to whom they’re proud to be bound by blood. Here’s how to figure out how closely related you are to all your cousins.

Lifehacker Image
Credit: Flowing Data

The handy chart above, from Nathan Yau at Flowing Data, makes the relationships pretty simple to determine. Here’s the explanation of how the chart works:

Figure out the common ancestor between two relatives. Then pick

the

first relationship to that ancestor

on

the top row, and follow

down until you match up with the other family member

. The result is how the first is related to the second.

Or, if you prefer, here’s a handy glossary of cousin terms.

Cousins

Your cousins are people with whom you share a common ancestor, and the most recent common ancestor you share is at least two generations away. That distinguishes them from, say, your siblings, who are the people with whom you share common ancestors that are one generation away—those common ancestors are your parents.

First cousins

Your first cousins are the children of your aunts and uncles. First cousins share a grandparent (i.e., your grandparents are two generations away from both you and your first cousins).

Second cousins

Second cousins share a great-grandparent and are the children of first cousins. So the kids of your dad’s first cousin are your second cousins.

Third cousins

Third cousins share a great-great-grandparent and are the children of second cousins. The kids of your dad’s second cousin are your third cousins. Are you sensing a pattern here? Fourth cousins share a great-great-great-grandparent and so on.

Once removed

If you’re “removed” from a cousin, that means you’re from different generations. If you’re “once removed” from a cousin, that means you are separated by one generation. Your dad’s first cousin is your first cousin, once removed. Your first cousin’s daughter is also your first cousin, once removed.

Twice removed

If you’re “twice removed” from a cousin, you are separated by two generations. Your grandmother’s first cousin is your first cousin, twice removed. The granddaughter of your first cousin is also your first cousin, twice removed.

This article was originally published in November 2014 and updated on Dec. 4, 2020 to include a revised chart, additional attribution, and clearer and more thorough information.