What Is A Third Cousin?

Have you ever heard the phrase ‘third cousin’ and not known what it meant? Does plotting your family tree confuse you when you get to your broader family? Understanding how people are related to you can be confusing. 

This post may contain affiliate links. I will earn a small commission, at no extra cost to you, if you make a purchase through an affiliate link.​

If this is the case, we are here to help you by explaining what a third cousin is. To get to this level, we have also defined first and second cousins so that you can better understand the concept of the third cousin. In some cases, we have included examples to aid you further. 

group of third cousins sitting together and smiling

There are different types of cousins, which will depend on how you are related to them. This will be designated by the number placed before the word “cousin.”

First Cousins

A cousin is a member of your family who is the child of your aunt or uncle. You will share a set of grandparents with your first cousins.

This means you are more closely related to your first cousins than your second or third cousins. You will likely share some DNA with your first cousin. As a result, you are quite closely related to first cousins. 

A fictional example of cousins can be found in The Fresh Prince of Bel-Air. The protagonist of the television series, Will, is cousins with Carlton Banks. Carlton is the son of Will’s aunt Vivian and uncle Phil.

Will’s other cousins are Hilary and Ashley. For a real-life example, we will use the British Royal Family. Prince Harry, Duke of Sussex is cousins with Princess Eugenie. 

Did you know that you and your third cousins share great-great-grandparents? Find out who they are!

Second Cousins

Second cousins are more complex than first cousins. You are less closely related to second cousins than you are to first cousins.

With second cousins, you will share great-grandparents. As a result, your relationship can be traced a generation further back than first cousins. A lot of families will have at least twenty cousins. 

Third Cousins 

As you might have guessed by now, third cousins are even more distantly related to you than your first and second cousins.

You will share your great-great-grandparents with your third cousins. Essentially, your third cousin will be the child of your parent’s second cousins. 

Very little DNA will be shared between third cousins.

Because of this, you can legally marry your third cousin in most places.

Though it will depend on the size of your family, most people have hundreds of third cousins. Many people do not even know most of their third cousins or will not have met them, since they are not very intimately related. 

What Are Cousins Who Have Been ‘removed’?

This is another term that many confuse many. A cousin who is once removed is from a different generation to you.

While first, second, and third cousins are in the same generation as you, cousins who are removed are not. If there is one generation gap between you, then you are considered first cousins once removed.

Understanding this concept is often harder than comprehending the different levels of cousins. If there is a two-generation gap, you will be first cousins twice removed. You can also have second cousins who are once removed, and so on.

Did you know that you and your third cousins share great-great-grandparents? Find out who they are!

two third cousins smiling together

Frequently Asked Questions

Because it can be quite challenging to comprehend your familial relationships with people, there are many questions surrounding second and third cousins. Fortunately, we have taken the time to answer some of these questions. 

Are Third Cousins Considered Part Of Your Family?

Yes, third cousins are considered part of your family since you will be distantly related to them. On the other hand, most people would not consider their third cousins to be involved in their immediate families.

Immediate families are a way of describing your closest relatives. Immediate families only tend to include parents, siblings, husbands, wives, or children. However, some will have a broader definition of immediate family which will also include aunts, uncles, first cousins, nephews, and nieces.

Third cousins are unlikely to be included in this, though it will depend on what constitutes your immediate family. 

How Much DNA Do Third Cousins Have In Common?

The further back you go, the less DNA you will share with your family. For instance, you will probably have considerably more DNA in common with first cousins than you will have with your second or third cousins.

At most, you will only share around 2% of your DNA with third cousins. The average you will have in common is approximately 0.8%. However, depending on genetics, you might not share any DNA at all.

This is unlikely though since there is a 90% chance that you will share at least a small amount of DNA with a third cousin. 

Are Second Cousins Blood-Related?

Yes, second cousins are blood-related to one another. They will share more DNA than third cousins, but less than first cousins. 

What Are Fourth Cousins?

Fourth cousins are even further related to you than first cousins. You will only share great-great-great grandparents with your fourth cousins. Because of this, it can be difficult to calculate who your fourth cousins are.

In fact, most people tend to have over one thousand fourth cousins, though the total will be reliant on the size of your family. 

Did you know that you and your third cousins share great-great-grandparents? Find out who they are!

Final Thoughts 

Families can be very complicated. Being able to understand how you are related to someone else can be arduous and stressful. Thankfully, with the simple explanations above, you should now possess a deeper understanding of what defines first, second, and third cousins. 

If you are still struggling with this, it might be a good idea to create a family tree. Family trees are not literal trees. Instead, they are charts that are used to represent the structure of your family. Using them, you can keep track of all of your relatives.

To start, simply create a diagram for you, your parents, and any siblings you have. Begin developing your family tree by adding children, husbands or wives, grandparents, uncles, aunts, first cousins, nephews, nieces. In no time, you will be able to add your second and third cousins to your amazing family tree.

Use these genealogy forms to stay organized as you discover your family history!

Get more of our favorite resources here!