What is a second cousin?

Your second cousin is the child of your mom’s or dad’s first cousin. The two of you share great-grandparents, but not grandparents: one of your grandparents and one of theirs are siblings.

At a glance

What you share: Great-grandparents, but not grandparents.
Not to mix up: Your cousin’s child is a first cousin once removed.
Your kids & theirs: Third cousins to each other.

Example familyJasmine’s grandma Kate is the sister of Ethan’s grandpa Thomas. So Jasmine and Ethan are second cousins: they share great-grandparents, Patrick and Margaret Sullivan.

Jasmineyour second cousin

Marcusyour first cousin once removed

Catherine «Kate»your great-aunt

Patrick and Margaret Sullivanyour great-grandparents

Thomasyour grandfather

Jamesyour father

You

Ethan

How to tell if someone is your second cousin

Find the closest ancestors the two of you have in common, then look at what they are to you. If they’re your great-grandparents, and theirs too, you’re second cousins.

You can also count steps. From you up to your great-grandparents takes three: your parent, your grandparent, then them. A second cousin climbs the same three steps on the other side.

First cousins: share grandparents.
Second cousins: share great-grandparents.
Third cousins: share great-great-grandparents.

Heads-up

Second cousin or first cousin once removed?

This is the classic family mix-up. Plain first, second and third cousins are always in your own generation. When a cousin is a generation older or younger than you, the name gets a “removed.”

So your first cousin’s daughter isn’t your second cousin: she’s your first cousin once removed. Your mom’s first cousin is your first cousin once removed too, just one generation up instead of down.

The twist comes one generation down: your kids and your first cousin’s kids are second cousins to each other. They’re the same generation, and they share great-grandparents: your grandparents.

How to find your second cousins

Start with your mom and dad. Ask them to name their first cousins, the children of their aunts and uncles. Every son or daughter of those cousins is your second cousin.

Old holiday card lists are a great place to look, and so is the guest list from the last big family wedding. Your grandparents may know every branch by heart.

And the next generation?

Your second cousin’s children are your second cousins once removed, one generation down. Going up works the same way: your mom’s or dad’s second cousin is your second cousin once removed too.

And your children and theirs? Third cousins. They share great-great-grandparents, one more step back.

In everyday talk, most people skip the numbers and just say “my cousin.” That’s perfectly fine. The numbers help when you’re putting together a family tree, or when you want to know exactly how two people fit together.

In real life

The cousins you meet at reunions

Most families have second cousins they see once a year, if that. You run into them at a summer reunion under a park shelter, at a wedding, or at a graduation party in someone’s backyard.

Somebody always asks, “Now, whose side are you from?” The grown-ups trace it back to the great-grandparents. The kids skip all that, and by sundown the second cousins are all on the same kickball team.