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What Is A Cousin?

What makes someone your cousin? The fact that you share an ancestor together makes you cousins. But to understand the intricacies of cousin relationships, you have to get this: Your ancestors are only the people in your direct line: parents, grandparents, great-grandparents, etc. Your ancestors’ siblings are aunts and uncles (no matter how many greats you add)—not ancestors. Just about any other blood relative who isn’t your sibling, ancestor, aunt, or uncle is your cousin. To determine your degree of cousinhood, you need to identify the ancestor you share with your cousin and how many generations separate each of you from that ancestor.

First cousins - Your first cousin (sometimes called a full cousin, but usually just a cousin) is the child of your aunt or uncle. The most recent ancestor you and your first cousin share is your grandparent. You typically share 12.5 percent of your first cousin’s DNA.

Second cousins - Your second cousins are the children of your parents’ first cousins. Take a look at your family tree, and you’ll see that you and your second cousins have the same great-grandparents. You typically share 3.125 percent of your second cousin’s DNA.

Third cousins - Of course, cousinhood doesn’t end there. You have likely also heard the term third cousin and wondered what that means. For third cousins, great-great-grandparents are the most recent common ancestor, and you share .781 percent of your DNA. You get the picture.

What is a second cousin once removed? The answer is simple: All cousins share a common ancestor. Your “degree of cousinhood” (second, third, fourth) depends on how many generations back that common ancestor is. Knowing this, you can make your own cousin calculator. Take your first cousins, who you know are your aunts’ and uncles’ children. You all have the same grandparents. Your second cousins share a set of great-grandparents with you, your third cousins have the same great-great grandparents, and so forth.

There are easy-to-use kinship charts on the internet for you to download and use. I always use pencil on my charts to easily change any mistakes I make.

Common Ancestor L. J. Smith

Child Odell Smith

Grandchild Susan

Great Grandchild

Great-Great Grandchild

Continue as far back as needed

Child C. D. Smith

Brother / Sister

Nephew/ Niece

Grand Nephew Niece

2nd Great Nephew Niece


Grandchild C. D. Smiths Children

Nephew Niece

1st Cousin

1st Cousin Once Removed

1st Cousin Twice Removed


Great Grandchild






Great-Great Grandchild






Continue as far back as needed






This chart can be continued as far as you need it to go. This is just an example of the chart I use with my research.

  1. To Use the Relationship Chart                 First, find your common ancestor on the top row.                 Second, find the relationship of the other person to the common ancestor in the left column. Where the row and column intersect is your relationship to that person.      Example:    You are the great-grandchild of your Ancestor.   The other person is the great-great-grandchild of the same Ancestor.

  2. You are the third one to the right from the Common Ancestor at the top of the chart.

  3. The other person is the fourth one down from the Common Ancestor on the left column.

  4. They intersect at 2nd cousin, once removed.    That is your relationship to the other person.

When the word "removed" is used to describe a relationship, it indicates that the two people are from different generations. You and your first cousins are in the same generation (two generations younger than your grandparents), so the word "removed" is not used to describe your relationship.

The words "once removed" mean that there is a difference of one generation. For example, your mother's first cousin is your first cousin, once removed. This is because your mother's first cousin is one generation younger than your grandparents and you are two generations younger than your grandparents. This one-generation difference equals "once removed."

Twice removed means that there is a two-generation difference. You are two generations younger than a first cousin of your grandmother, so you and your grandmother's first cousin are first cousins, twice removed.

I hope this helps you in your cousin research!





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