What is a First Cousin?

Marc McDermott
February 3, 2022

Whether you’re close to yours or not, many people know their cousins. As part of the same generation, first cousins are an easy part of the family tree to trace. 

First cousins are the children of siblings. So your parents’ brothers’ and sisters’ children are all your first cousins. You may be close to these relatives because they are a similar age, possibly at a similar stage in their life and their children and your children may have the same closeness as a result. 

We’re going to take a closer look to get to know all the important details of first cousins to help you better understand your family tree. 

How is a first cousin related to me?

A first cousin is related to another by sharing a set of grandparents. Second cousins share great-grandparents, and third cousins share great-great-grandparents and so on. First cousins are the children of their grandparents’ children so your aunts and uncles are the parents of your first cousins. 

first cousins

What is an example of a first cousin?

An example of a first cousin is as follows… your mother or father have siblings. If these siblings have offspring, their offspring are your first cousins. You are part of the same generation. 

You share the same grandparent(s) and are often of a similar age. 

Are first cousins considered family?

Yes, they are. Cousins, siblings, uncles, grandparents are all family. Cousins are usually considered to be close relatives, and second cousins are less so. Family members who are closely related share more of the same DNA, and first cousins are as close to your immediate family as can be. Other than siblings and parents, they are as close to immediate family as possible. 

In terms of the law, first cousins are often considered close family. In the USA, first cousins are often thought of like family for legal purposes to do with funerals and even commercial contracts so it is best to check with your state authority if you need clarification.

In society, a lot will depend on what constitutes a family. It may be the case that only close family are invited to a wedding, but some people have a different take on what qualifies as close, so first cousins may or may not receive the invite.

Immediate family does not usually indicate first cousins, but close family may be a better way of describing the relation. 

Are first cousins blood-related?

First cousins are blood relatives when you share a common ancestor(s). This is for either the maternal or paternal side, as the children of your uncles and aunts are your first cousins. Only adopted members of the family are not blood relatives. 

Another example is if a cousin is a relation through marriage, then they are not blood relatives. If your aunt married a man who had a child from their prior relationship then you may call this child your cousin and grow up knowing them as your cousin, but they are not blood relatives.

The amount of DNA that first cousins share can vary from around 7% to 13.8%. On average, first cousins share around 12.5% DNA. This figure is the result of different inherited amounts of DNA, also from common ancestors. For example, one cousin will receive different sections of DNA from a grandparent than another. Each generation the DNA is passed down to decrease the amount of DNA found.

What grandparents do first cousins share

First cousins share at least one grandparent. Second cousins share a great-grandparent, third cousins share a great-great-great-grandparent, and so on. The cousinhood degree of first, second, third, fourth, fifth, etc indicates the number of generations between the parents of any two cousins. 

As the children of siblings, first cousins always share a mutual grandparent.

How many first cousins does the average person have?

This will depend on how many children your uncles and aunties have. In the past, it was not unusual for families to have close to ten children, sometimes more. This means if your grandparents had ten children, these siblings could go on to have multiple children, increasing the number of first cousins you have. 

Birth rates are an important part of predicting the number of first cousins anyone can have. Even if yours has an average of 5 first cousins per family, this doesn’t mean you will necessarily be close to that figure. 

What does first cousin once removed mean?

First cousins not in the same generation are likely to be once removed. The child of a first cousin is known as a first cousin once removed. 

So, you are the first cousin once removed from the first cousin of your parents. Your common ancestor is your great-grandfather. This means you are first cousins but with a generation between you. Therefore, you are first cousins once removed. 

The number of times you are removed from a cousin is in the number of generations that separate you.

What does first cousin twice removed mean?

Twice removed means there is a difference of two generations between two relatives, A first cousin twice removed will be your grandparent’s first cousin or your first cousins’ grandchild. 

The two generations between you and your grandparent’s first cousin, and your first cousin’s grandchild is an indication of this. 

What is a half-first cousin?

If you have been told you have multiple half cousins then this is not uncommon as there are various ways this situation can arise. It is also possible to have multiple half first, second, third cousins, and so on.

Half cousins typically share around half the DNA of full cousins. With only one ancestor in common from your grandparents, you will have half first cousins. To have half cousins, one member of the family must remarry and have children with more than one person. A grandparent can have offspring with two different people, making their offspring half-siblings, and therefore half-cousins when they have offspring.

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