What Is a Second Cousin? Meaning, Chart and Examples

A second cousin is a relative who shares great-grandparents with you but not grandparents. Put another way, your second cousin is the child of your parent's first cousin, or the grandchild of your grandparent's brother or sister. The two of you belong to the same generation, each three steps below the ancestors you have in common.

The quick test for a second cousin

Ask one question: who is the closest ancestor we both descend from?

• If the answer is a grandparent, you are first cousins.
• If the answer is a great-grandparent, and you are both great-grandchildren of that person, you are second cousins.
• If the answer is a great-great-grandparent, and you are in the same generation, you are third cousins.

The FamilySearch genealogy blog offers a handy shortcut: count the "greats" in the shared ancestor's title and add one. A great-grandparent has one "great," so one plus one makes second cousins. The shortcut only works when both people are the same number of generations from that ancestor.

A worked example: the Hale family

Here is an invented family to make it concrete. Walter and Edith Hale married and had two children, Ruth and Frank.

• Ruth had a daughter, Diane. Frank had a son, Paul. Diane and Paul share grandparents (Walter and Edith), so they are first cousins.
• Diane had a daughter, Maya. Paul had a son, Leo. Maya and Leo share great-grandparents (Walter and Edith), so they are second cousins.
• Maya has a son, Sam. Leo has a daughter, Nora. Sam and Nora share great-great-grandparents, so they are third cousins.

Notice what Maya would say in everyday speech: "Leo is my mom's cousin's son." That phrase, a parent's cousin's child, is the plainest description of a second cousin. From the other direction, Maya's grandmother Ruth and Leo's grandfather Frank were sister and brother.

Second cousin chart

Each row is one generation of the Hale family. People on the same row, in different branches, are cousins of the same degree.

Generation	Ruth's branch	Frank's branch	How the two are related
Children of Walter and Edith	Ruth	Frank	Siblings
Grandchildren	Diane	Paul	First cousins
Great-grandchildren	Maya	Leo	Second cousins
Great-great-grandchildren	Sam	Nora	Third cousins

Relationships that cross rows are the "removed" ones. Diane and Leo sit one row apart, so they are first cousins once removed. Maya and Nora sit one row apart as well, and they are second cousins once removed.

Second cousin vs first cousin once removed

This is the mix-up that causes most family arguments. The two terms describe different people.

• A second cousin is in your generation. You share great-grandparents. For Maya, that is Leo.
• A first cousin once removed is one generation above or below you. It is either your parent's first cousin or your first cousin's child. For Maya, that is Paul, her mother's first cousin.

The two are linked in a tidy way: the parent of your second cousin is your first cousin once removed. Paul is Maya's first cousin once removed, and Paul's son Leo is her second cousin. If you can name one, you can find the other.

A common mistake is to call a cousin's child a "second cousin." Your first cousin's child is your first cousin once removed. It is your children and your first cousin's children who are second cousins to each other. Our guide to what "once removed" means covers the counting rule for every combination.

What is a second cousin once removed?

"Once removed" means one generation apart. A second cousin once removed is therefore either of two people:

• the child of your second cousin (one generation below you). For Maya, that is Nora, Leo's daughter.
• the second cousin of one of your parents (one generation above you). For Sam, that is Leo, his mother's second cousin.

The term works in both directions, so Nora and Maya are each other's second cousin once removed. In terms of shared ancestors, one of you is a great-grandchild of the common couple and the other is a great-great-grandchild.

A second cousin twice removed is two generations away: your second cousin's grandchild, or your grandparent's second cousin.

What to call the children of second cousins

• Your second cousin's child is your second cousin once removed.
• Your child and your second cousin's child are third cousins to each other.
• Your grandchildren and your second cousin's grandchildren are fourth cousins.

Each new generation on both sides adds one to the cousin number. In daily life, of course, most families just say "cousin" and save the exact term for the family tree.

How much DNA do second cousins share?

On paper, second cousins are expected to share about 3.125 percent of their DNA, which is one part in thirty-two. The figure comes from the coefficient of relationship, a standard measure that halves with each generation separating two relatives from their common ancestors. For comparison:

• first cousins: 12.5 percent;
• first cousins once removed: 6.25 percent;
• second cousins: 3.125 percent;
• second cousins once removed: about 1.56 percent;
• third cousins: about 0.78 percent.

Two cautions. First, these are expected values calculated from the tree, not measurements of any particular pair. Second, the numbers assume the usual case in which the cousins share a great-grandparent couple. Half second cousins, who share only one great-grandparent because their grandparents were half siblings, are expected to share half as much, about 1.56 percent.

DNA testing services report matches in centimorgans, a unit for the amount of DNA two people have in common, and then suggest a likely range of relationships. A match labeled "second cousin" is an estimate. The paper trail, meaning the names and dates that connect both of you to the same great-grandparents, is what confirms it.

Finding and recording your second cousins

1. List your eight great-grandparents, or as many as you can name. Each couple is a possible source of second cousins.
2. List your grandparents' brothers and sisters. Their grandchildren are your second cousins.
3. Ask older relatives who came to weddings, funerals and reunions. Second cousins are often the people in the photographs nobody can quite name.
4. Write the link in plain words beside the formal term: "second cousin (grandson of Grandma Ruth's brother Frank)."

If you have not drawn your tree yet, our step-by-step guide on how to make a family tree shows where the great-grandparents' other descendants fit.