What is a Fourth Cousin? - Genealogy Explained (2024)

What is a fourth cousin and how are we related to one another? It can be difficult to track your family tree the bigger it seems to get, so we’re going to cover all the burning questions about fourth cousins.

The more generations involved, the more complicated it becomes to research a family tree. To shed some light on the ins and outs of fourth cousins, we’ll cover topics such as whether or not they share DNA, what being a half-fourth cousin means, “removed” fourth cousins, and a lot more.

In this article: show

So, what is a fourth cousin?

A fourth cousin is someone who shares a set of great-great-great-grandparents with you. Essentially, they are the descendants of a sibling of your great-great-grandparents. Any number of cousins is an example of how many generations you are away from your common ancestor.

So second cousins share a great-grandparent, and third cousins share a great-great-grandparent. Subsequently, fourth cousins share a great-great-great grandparent, marking what is the 5th generation in your family tree.

Pro tip: Now that you understand fourth cousins, why not explore your family’s unique story? Try MyHeritage’s 14-day free trial to delve into billions of records and uncover your family’s tale. What stories await in your family tree?

How is a fourth cousin related to me?

A fourth cousin is related via great-great-great-grandparents. Fourth cousins are both descendants from the same number of generations away from a common ancestor – when considering fourth cousins, this is five generations.

A fourth cousin that is once removed is a child of your fourth cousin. Two cousins that share the common ancestor but do not share the same number of descending generations are considered “removed”

Those closest to the common ancestor set the cousin relationship, whether this is first, second, third, fourth, etc. “Removed” is used to calculate from this person’s generational level.

Are fourth cousins considered family?

Although fourth cousins do not seem to be close in relation, they are considered family. Some may say they are not close family, but with DNA shared with some cousins, it is prudent to say fourth cousins are family.

Are fourth cousins blood-related?

Because you only share DNA with around half of your fourth cousins, there is a chance that you are not “blood-related.”

If you have a half-fourth cousin, it is more likely that you do not share identical DNA. You may be genetically related to each of your fourth cousins, but it is possible to not share DNA with all of them.

Fourth cousins share a great-great-great-grandparent. This, in turn, means second cousins share a great grandparent and third cousins share a great-great-grandparent.

It is possible to share a complete set of great-grandparents with a fourth cousin, although anyone who shares one great-great-great grandparent would technically be a half-fourth cousin.

With 32 great-great-great-grandparents, you will share 2 of the 32 with a fourth cousin. For a half-fourth cousin, you will only share 1 out of the possible 32 great-great-great-grandparents.

How many fourth cousins do I have?

The number of relatives anyone has in a generation can depend on a handful of variables.

To start, if all your great-great-great-grandparents had lots of kids and their kids survived to become adults and had lots of kids themselves, then you are more likely to have more fourth cousins than the average family tree.

However, other factors including not having multiple kids, war, illness, natural disasters, and other factors can reduce the number of fourth cousins you have. This can mean you have fewer fourth cousins than the average person, so it is difficult to put an exact number on how many fourth cousins anyone has.

What does fourth cousin once removed mean?

The child of your fourth cousin or the fourth cousin of your parent is known as a fourth cousin once removed. Two cousins that share a common ancestor but are not the same number of generations from great-grandparents are said to be “removed.”

Cousins that are not removed share the same generation. To put this into context, a first cousin is the child of your parent’s brother or sister. As your parents and their siblings were part of the same generation, so are you and their siblings’ children.

No matter which cousin it is, a cousin that is once removed is one generation above or below another.

This means your mom’s first cousin is your first cousin, but he or she is once removed because of the generation between the two of you.

If your fourth cousin was to have a child then their child would be once removed because they are one generation below you.

What does fourth cousin twice removed mean?

For there to be “removed” in a relationship, the cousins must not share the same generation. A fourth cousin that is twice removed is a fourth cousin who is two generations away from yours, either older or younger.

If a cousin is not removed, it means they are part of your grandparents twice removed, it means your cousin will either be a part of your grandparent’s generation or the same generation as your grandchildren as there are two generations between you.

What is a half-fourth cousin?

Anyone descended from a half-sibling of your great-great-grandparents is considered your half-fourth cousin.

Essentially, you only have one mutual great-great-great grandparent in common. It is important to distinguish between the two when researching a family tree if you are following your bloodlines and heritage.

Final word

To sum it up, two people that share one great-great-great-grandparent but not the other are half-fourth cousins.

Read more about kinship.

What is a Fourth Cousin? - Genealogy Explained (2024)

FAQs

What does 4th cousin mean on ancestry? ›

If you and a cousin share great-grandparents (2 "G"s), you are second cousins. If you and a cousin share great-great-grandparents (3 "G"s), you are third cousins. If you and a cousin share great-great-great grandparents (4 "G"s) you are fourth cousins, and so forth.

How much DNA do you share with 4th cousin once removed? ›

Table
% sharedTotal cM shared half-identical (or better)Relationship
0.391%26.56Third cousins once removed
0.195%13.28Fourth cousins, third cousins twice removed
0.0977%6.64Fourth cousins once removed. third cousins three times removed
0.0488%3.32Fifth cousins
11 more rows

How many generations back is a fourth cousin? ›

A fourth cousin is related via great-great-great-grandparents. Fourth cousins are both descendants from the same number of generations away from a common ancestor – when considering fourth cousins, this is five generations.

How genetically close are fourth cousins? ›

On average, you will share more DNA with a third cousin than fourth; however, a few fourth cousins could share more DNA with you than a particular third cousin shares with you. As an example, a maternal fourth cousin might share more autosomal DNA with you than a paternal third cousin.

How much blood do 4th cousins share? ›

Average Percent DNA Shared Between Relatives
RelationshipAverage % DNA SharedRange
2nd Cousin3.13%2% - 6%
2nd Cousin once removed Half second cousin1.5%0.6% - 2.5%
3rd Cousin0.78%0% - 2.2%
4th Cousin0.20%0% - 0.8%
7 more rows

How many generations until you are no longer related? ›

Based on a family tree, you are always genealogically related, but you may not be genetically related. After about 8 generations, you have genetic material from fewer and fewer of your ancestors. After 16 generations, you only have DNA from about 2% of your ancestors, and it keeps decreasing.

How many fourth cousins does the average person have? ›

How many cousins do we have?
RelationshipNumber of cousins
Second cousins28
Third cousins175
Fourth cousins1,570
Fifth cousins17,300
2 more rows

Why does Ancestry say my brother is my cousin? ›

Someone in this category is likely a brother or sister who shares both biological parents with you. In the rare situation that you have a half sibling who is also your first cousin, they may appear in this category too.

Can you marry a fourth cousin? ›

For example in Maine the marriage is allowed if the pair receive genetic counselling conducted by a physician. It is not illegal to marry your fourth cousin in any state because only 0.2 percent of DNA is shared between the relatives, as opposed to 12.5 percent with a first cousin.

At what point are cousins not related? ›

For a relative to be “removed,” cousins cannot share a generation. This means a second cousin that is twice removed is a cousin that is two generations away from another, either older or younger. Cousins that are not removed mean they are part of your grandparent's side but twice removed.

Who is your closest blood relative? ›

Who is my nearest relative?
  • Husband, wife or civil partner (including cohabitee for more than 6 months).
  • Son or daughter.
  • Father or mother (an unmarried father must have parental responsibility in order to be nearest relative)
  • Brother or sister.
  • Grandparent.
  • Grandchild.
  • Uncle or aunt.
  • Nephew or niece.

What's the farthest cousin you can have? ›

You may discover many of your 4th and 5th cousins—and sometimes even your 8th or 10th cousins.

Why do I have so many fourth cousins on Ancestry? ›

Your relationship to people in the fourth cousin categories and further out may not always be due to a recent shared ancestor. It may be due to DNA that's common in a population you both come from.

Are you more related to your sibling or child? ›

Like siblings, parents and children share 50 percent of their DNA with one another. While the shared DNA between full siblings includes 25 percent of the mother's DNA and 25 percent of the father's DNA, the DNA shared between a parent and child is 50 percent of that parent's DNA.

Who is genetically closer half-sibling or cousin? ›

Does this mean you're more related to your half-sibling than your cousin? Since you do only share 12.5% DNA with your first cousin, then technically, yes, you are more related to your half-sibling than your cousin since you share 25% of your DNA with your half-sibling.

Is 4th or 5th cousins blood related? ›

This means that if you meet your 4th cousins (i.e. your great-grandparents were cousins) your genealogical relationship is mostly academic and barely based on “blood”! By 5th cousins, you're no more related than you are to the random person on the street in terms of common DNA.

How is a 4th to 6th cousin related to me? ›

A 4th cousin means the people share a 3 great grandparent and a 6th cousin means they share a 5 great grandparent. if you share a cousin that would mean you also would have that same relationship with each other. That is you are 4th cousins to each other.

What is the difference between 3rd and 4th cousins? ›

Third, Fourth, and Fifth Cousins: Your third cousins share at least one great-great-grandparent, fourth cousins share a great-great-great-grandparent, and so on. Removed: When the word “removed” is used to describe a relationship, it indicates that the two people are from different generations.

Why does AncestryDNA say my sister is my cousin? ›

Summarizing what we've learned. It's common for people to have half-siblings since not all children share the same two parents. When you take the Ancestry DNA test, since half-siblings only share 25% of their DNA, they may be categorized as your first cousin.

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