What is a Fourth Cousin? (2023)

What is a fourth cousin? How many fourth cousins does the average person have? In this post, you’ll learn the answer to these questions, as well as:

  • What is a fourth cousin once-removed?
  • Whether fourth cousins share DNA
  • What is a half-fourth cousin?
  • Are fourth cousins blood related?
What is a Fourth Cousin? (1)

Most people grow up knowing only their first and second cousins. Only rarely will someone know a third or fourth cousin personally and know how they are related.

So, it is understandable that the exact cousin relationship between these two cousin types is a bit confusion. My goal is that this post clears everything up for you.

What is a fourth cousin?

A fourth cousin is a person who shares one set of great-great-great grandparents with you. Another way to think about it is that a fourth cousin is descended from a sibling of your great-great grandparent.

In order to be a fourth cousin without any generations “removed”, you both must be the same number of generations descended from your great-great-great grandparent. You and your fourth cousin must both be the great-great-great grandchildren of that common ancestor.

The other bit of information that is important to explain in more detail is that you also must be descended from different children of that 3rd great-grandparent. If you and your cousin are both descended from the same child of the ancestor, then you might be third cousins.

Fourth cousins are relatives descended from our common ancestor on collateral lines of our family tree.

(Video) What is a Second to Fourth Cousin? - Genetic Genealogy Explained

Fourth cousins share which grandparent?

To put it simply, fourth cousins share at least one great-great-great grandparent. This ancestor is also known as the most recent common ancestor.

The image below shows an example of fourth cousins. The “ancestors” are Abel and Maria. Two of their children are displayed in the example, and you can see how the descendants of their children are related.

What is a Fourth Cousin? (2)

To explain the graphic even further:

  • The children of Abel and Maria are siblings
  • The grandchildren of Abel and Maria are first cousins
  • The great-grandchildren of Abel and Maria are second cousins
  • The great-great grandchildren of Abel and Maria are third cousins
  • The great-great-great grandchildren of Abel and Maria are fourth cousins

As long as the descendants of Abel and Maria are the same number of generations removed from the common ancestor (in the case of fourth cousins, five generations), they are fourth cousins.

If Abel and Maria’s great-great-great grandchild would like to know how to describe their exact relationship to a cousin who is of a different generation (i.e. Abel and Maria’s great-great grandchild), then they will have to read the next section about fourth cousins once-removed.

If you have a fourth cousin who is descended from a sibling of your great-great grandparent who married a sibling of a great-great grandparent of a different line of your family, then you have a double-fourth cousin. You can read more about double-fourth cousins here:

  • What is a double fourth cousin?

What is a fourth cousin once-removed?

A fourth cousin once-removed is the child of your fourth cousin or the fourth cousin of your parent (i.e. you are the child of the fourth cousin).

When two cousins share the same common ancestor but don’t share the same number of generations in descent from said ancestor, we use the term “removed“.

(Video) 4th Cousin | How much DNA do you share?

The person who is the closest to the common ancestor sets the cousin-relationship type (i.e. first/second/third/fourth cousin) and then the “removed” is calculated from that’s person’s generation level to the other cousin.

For example, in the case of fourth-cousin once-removed, we know that a fourth cousin is a great-great-great grandchild of the common ancestor. If the other cousin is the great-great-great-great grandchild, then there is one generation difference between them and they are fourth cousins once-removed.

What is a fourth cousin twice-removed?

If your relative is grandchild of a fourth cousin, then they are fourth cousins twice-removed. The common ancestor shared is still your great-great-great grandparent, but that ancestor is the great-great-great-great-great grandparent of your fourth-cousin twice-removed.

If there are more than two generations between the cousins, then you just keep counting, adding the number of generations removed. For example, a great-grandchild of your 4th cousin is a fourth-cousin three-times removed.

What is a half-fourth cousin?

As you now know, a fourth cousin is someone that is descended from a full sibling of your great-great grandparent. You share both great-great-great grandparents with your fourth cousin.

A half-fourth cousin is a person who is descended from your great-great grandparent’s half-sibling. In other words, you only share one great-great-great grandparent in common.

For some people researching their family tree, distinguishing between full and half-fourth cousins is very important. This is especially true when it comes to those who use DNA to research their family trees.

Half-fourth cousins will share less DNA, on average, as full fourth cousins.

(Video) Cousins Explained

How many fourth cousins do I have?

Any given person might have 940-1500 4th cousins, or more. However, the actual number of relatives that you have on any generation depends on lots of variables.

For example, if all of your great-great-great grandparents had lots of kids, and all of those kids survived to adulthood and had lots of kids themselves, then you might have more 4th cousins than the average person.

Alternatively, if your ancestors and their descendants were affected by natural disasters, wars, famines, and illness, you might have fewer fourth cousins than average.

It might be possible to track down all of your fourth cousins, but it would likely take years of work. Plus, if you have ancestors that lived in other countries 150 years ago, your 4th cousins might be located all over the world.

Are fourth cousins blood related?

Will 4th cousins be blood related, or share DNA? You will only share genes with about 50% of your many fourth cousins.

This is because we don’t actually share DNA with all of our relatives. Furthermore, 4th cousins are considered to be distant cousins.

The amount of DNA that you will share with a fourth cousin with whom you do share DNA is will be small. The 4th cousin DNA percentage shared is .19%, which works out to about 14 centimorgans.

If you have 940 4th cousins and all of them took a DNA test, statistics tell us that only about 470 of those cousins would show up as DNA matches to you. In other words you are related genealogically to all of your fourth cousins but you might not share DNA.

(Video) What's a Second Cousin Once Removed?

Furthermore, if your fourth cousin is a half-fourth cousin, there is a higher chance that you will not share any identical DNA.

A true 4th cousin can be different than a fourth cousin DNA match. If you want to learn about fourth cousin DNA matches on sites such as Ancestry DNA, click here:

  • What is a fourth cousin DNA match on Ancestry DNA
What is a Fourth Cousin? (3)

Conclusion

I hope that this post helped you understand more about fourth cousins, how many fourth cousins you have, and whether fourth cousins are always “blood related” (whether they share DNA).

While it’s not very common to grow up knowing any of your fourth cousins personally, it is not impossible! Other times, we get to know our fourth cousins by accident through our genealogy research.

If you have any questions about something that you read in this post, or if you would like to share your own experience finding fourth cousins, I would love to hear from you in the discussion below

Thanks for stopping by today!

FAQs

Is a 4th cousin a blood relative? ›

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.

How closely related are 4th cousins? ›

First cousins share a grandparent (2 generations) Second cousins share a great-grandparent (3 generations) Third cousins share a great-great-grandparent(4 generations) Fourth cousins share a 3rd-great grandparent (5 generations)

Is it OK to marry 4th cousin? ›

It's legal everywhere to marry a third or fourth cousin.

Even first cousins can marry in most places. Second cousins can probably marry everywhere. The risk of having a child with a fourth cousin is probably just as high as having a child with an unrelated person of the same ethnicity.

Do all 4th cousins share DNA? ›

You and your cousin's children are 12.5% half-identical, and so on and so on. Fourth cousins are on average just 0.4% half-identical with each other. That means that half-fourth cousins would be only 0.2% half-identical.

Is it OK to marry 3rd cousin? ›

Myth and Fact About Marriages Between Cousins

In short, yes, it is legal for second and third cousins to marry in the US.

Is it OK to date your 4th cousin? ›

Third cousins only share 0.78% of their genes and fourth cousins only share 0.20% so nothing is stopping you. It's legal everywhere to marry a third or fourth cousin. Even first cousins can marry in most places.

What is a fourth cousin DNA match? ›

A fourth cousin designation just means that you and your match are separated by between six and twelve degrees (people). So that might be five back on your chart to your common ancestor, and five down to your match, which would make you true fourth cousins. It could also be some other permutation of that.

Are 5th cousins blood related? ›

Are Fifth Cousins Blood-Related? Fifth cousins are related, but there is a chance they do not share DNA. In fact, there is only a 10-15% chance of sharing genetics with any fifth cousin. Even if you and our fifth cousin are related by blood, the DNA shared will be small, especially when compared to closer cousins.

Which grandparent are you most related to? ›

Both scientific surveys and anecdotal evidence show that typically maternal grandparents are closer to grandchildren than paternal grandparents. 1 The usual ranking goes like this, from closest to least close: maternal grandmother, maternal grandfather, paternal grandmother, paternal grandfather.

What do 4th cousins have in common? ›

A fourth cousin is a person who shares one set of great-great-great grandparents with you. Another way to think about it is that a fourth cousin is descended from a sibling of your great-great grandparent.

What cousin is too close marriage? ›

In the United States, second cousins are legally allowed to marry in every state. However, marriage between first cousins is legal in only about half of the American states. All in all, marrying your cousin or half-sibling will largely depend on the laws where you live and personal and/or cultural beliefs.

Which cousin can you not marry? ›

Twenty-four states prohibit marriages between first cousins. Twenty states and the District of Columbia allow cousins to marry; six states permit first-cousin marriage only under certain circumstances.

Where in the Bible does it say not to marry your cousin? ›

This "Levitical law" is found in Leviticus 18:6-18, supplemented by Leviticus 20:17-21 and Deuteronomy 27:20-23.

Can a half sibling show up as a cousin? ›

Can a half-sibling show up as a cousin? While the amount of DNA you share is different between half-siblings and cousins, your half-sibling still may show up as a “first cousin” because your centimorgans may be within the 1,300 range.

What would my mom's first cousin be to me? ›

Similarly, your mom's cousin is your first cousin once removed, because his grandparents are your great-grandparents. There is a generational difference. However, your mom's cousin's CHILD is your second cousin with no “removed” added, because the two of you share the same great-grandparents.

Are all humans cousins? ›

The human genome project has revealed to us long ago that there are no genetically distinct and pure groups of humans. We are all cousins.

How far of a cousin Can you marry? ›

Laws regarding first-cousin marriage in the United States

As of February 2014, 24 U.S. states prohibit marriages between first cousins, 19 U.S. states allow marriages between first cousins, and 7 U.S. states allow only some marriages between first cousins. Six states prohibit first-cousin-once-removed marriages.

Can a girl marry her second cousin? ›

Another important point worth noting here is that under the Hindu Marriage Act 1955 marriage with second cousins (father's first cousin's children) is also not allowed due to the restriction known as "sapinda" relationship [Section 5(v)].

How many cousins removed to marry? ›

As of February 2014, 24 U.S. states prohibit marriages between first cousins, 19 U.S. states allow marriages between first cousins, and seven U.S. states allow only some marriages between first cousins. Six states prohibit first-cousin-once-removed marriages.

What is my mom's cousin's grandchild to me? ›

Second cousins have the same great-grandparents as you. Think of it this way: your mom's first cousin's child is your second cousin. Or, your grandpa's brother's grandchild (your dad's aunt's grandchild) is your second cousin.

Are cousins blood relatives? ›

A blood relative includes a parent, brother, sister, aunt, uncle, nephew, niece, first cousin, or any of the aforementioned prefixed by "grand", "great-grand", or "great-great-grand."

What is my dads cousin to me? ›

Your dad's cousin is called your cousin once removed. That means they are one generation away from you.

How many generations does it take to not be related? ›

If people in this population meet and breed at random, it turns out that you only need to go back an average of 20 generations before you find an individual who is a common ancestor of everyone in the population.

What do you call a cousin that is not blood related? ›

Some people call a cousin's cousin a distant cousin rather than a cousin-in-law. The main thing to remember is that these cousins can be relatives, but if they are not part of your family tree via blood, then it is easier to refer to them as “in-law.”

What level of cousin is everyone? ›

Consider this: If you assume only two children to a couple (a quota actually too low to permit humanity to survive), everyone — on the average — must have 4 first cousins, 16 second cousins, probably 64 third cousins, about 250 fourth cousins, roughly 1,000 fifth cousins, and some million relatives as close as tenth ...

What genes are inherited from mother only? ›

Unlike nuclear DNA, which comes from both parents, mitochondrial DNA comes only from the mother.

Are you more related to mother or father? ›

Genetically, you actually carry more of your mother's genes than your father's. That's because of little organelles that live within your cells, the mitochondria, which you only receive from your mother.

What genes are inherited from father only? ›

All men inherit a Y chromosome from their father, which means all traits that are only found on the Y chromosome come from dad, not mom. The Supporting Evidence: Y-linked traits follow a clear paternal lineage.

Am I related to everyone my grandma is related to? ›

A common ancestor is someone you and a relative both descend from. For example, your parents, grandparents, and great-grandparents are all common ancestors to you and your siblings. The most recent common ancestor is the nearest-to-you shared ancestor.

Who are you most genetically similar to? ›

On average, we are just as related to our parents as we are to our siblings--but there can be some slight differences! We share 1/2 of our genetic material with our mother and 1/2 with our father. We also share 1/2 of our DNA, on average, with our brothers and sisters. Identical twins are an exception to this rule.

What do I call my cousins child? ›

Your cousin's child is NOT your second cousin as is commonly believed. The appropriate name for addressing your cousin's child is niece or nephew, even though they are actually first cousins once removed.

What do you call your parents cousin? ›

Your parent's cousin is your first cousin (once removed, as we'll explain in a minute!), not your second cousin, because even though the ancestor you share is your great-grandparent, that ancestor is your cousin's grandparent — and that's the shortest distance in generations between you.

What famous person married their cousin? ›

Edgar Allan Poe.

For his second marriage, the famed poet and author of “The Raven” wed his first cousin Virginia Eliza Clemm. The two were married when he was 27 and she was 13.

Can you marry your sister in Alabama? ›

Alabama Marriage Requirements

You cannot marry children, siblings, parents, uncles, aunts, grandchildren, grandparents or great grandparents of any relation. You can marry first cousins without restriction, however.

Is it worse to marry your first or second cousin? ›

Ultimately, marrying your first cousin carries some risk. But the odds of healthy offspring dramatically improve with each new distance of relation. Second cousins share only 6.25 percent of their genes and third cousins share just over 3 percent.

What happens if you marry your cousin and have a baby? ›

The vast majority of children of first cousins are healthy and do not have problems due to their parents' relatedness. It is important to keep in mind that even for an unrelated couple, there is an approximately 2-3% chance that their child is born with a birth defect, genetic syndrome, or disability.

Is second cousin inbreeding? ›

First cousins have an inbreeding coefficient of 0.0625. Anything at or above 0.0156, the coefficient for second cousins, is considered consanguineous; that includes relationships between people and their nephews and nieces.

What will happen if you have a baby with your cousin? ›

The majority of babies born to couples who are blood relatives are healthy. Whilst cousin marriage increases the risk of birth defect from 3% to 6%, the absolute risk is still small. Cousin marriage only accounts for a third of birth defects.

Is it OK to marry your 4th cousin? ›

It's legal everywhere to marry a third or fourth cousin.

Even first cousins can marry in most places. Second cousins can probably marry everywhere. The risk of having a child with a fourth cousin is probably just as high as having a child with an unrelated person of the same ethnicity.

Is it a sin to sleep with your cousin? ›

Also, cousins are not included in the lists of prohibited relationships. However, the Bible prohibits relationships with any close blood relative (Leviticus 18:6).

Is it sinful to live together before marriage? ›

The Church's teaching on cohabitation is not an “arbitrary” rule. Living together before marriage is a sin because it violates God's commandments and the law of the Church.

What is considered a blood relative? ›

blood relative. A person who is related by birth, rather than by marriage, including those of half-blood. A blood relative includes a parent, brother, sister, aunt, uncle, nephew, niece, first cousin, or any of the aforementioned prefixed by "grand", "great-grand", or "great-great-grand."

What cousin are not blood related? ›

Some people call a cousin's cousin a distant cousin rather than a cousin-in-law. The main thing to remember is that these cousins can be relatives, but if they are not part of your family tree via blood, then it is easier to refer to them as “in-law.”

Which cousins are blood related? ›

As the children of first cousins, second cousins are blood-related. Second cousins share great-grandparents and as first cousins share grandparents, the connection is halved with every new generation.

What level cousin can you marry? ›

In the United States, second cousins are legally allowed to marry in every state. However, marriage between first cousins is legal in only about half of the American states.

Can you be family without being blood related? ›

A chosen family is simply a family you choose. It can be made up of both of blood and nonblood-related people, or just one of them. It's what you make it. All a family needs to be is people who love and care about you.

Is everyone related by blood? ›

Basic math tells us that all humans share ancestors, but it's amazing how recently those shared ancestors lived. Thanks to genetic data in the 21st century, scientists are discovering that we really are all descended from one mother. It's Okay To Be Smart explores our common human ancestry.

What do you call your cousin's child? ›

They're both two generations away from the grandparents they share. If first cousins have children, the children are second cousins to each other. They're the same generation as each other, because they share a set of great-grandparents. If second cousins have children, the children are third cousins to each other.

Are cousins by marriage related? ›

What is this? Since a cousin-in-law is someone who enters your family by marriage and not blood, they are not considered a blood relation. They are also not a “close relative” in the same way that your siblings, parents, grandparents, or even to a lesser extent, your cousins (including the one they married).

Do you have the same blood as your cousin? ›

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.

What does the Bible say about marrying your cousin? ›

Must first cousins be forbidden to marry? In the Bible, and in many parts of the world, the answer is no. But the answer is yes in much of church law and in half the United States.

What is your moms cousin to you? ›

Similarly, your mom's cousin is your first cousin once removed, because his grandparents are your great-grandparents. There is a generational difference. However, your mom's cousin's CHILD is your second cousin with no “removed” added, because the two of you share the same great-grandparents.

Videos

1. Things Your Should Know About Fourth Cousins
(Ellen Thompson-Jennings - Family History Hound)
2. Is Marrying Your Cousin Actually Dangerous?
(Insider Science)
3. Fourth cousin Meaning
(ADictionary)
4. What does fourth cousin mean?
(What Does That Mean?)
5. fourth cousins Part I
(James Fonder)
6. QUICKLY See How Your DNA Matches Are Related to You
(Family History Fanatics)
Top Articles
Latest Posts
Article information

Author: Carlyn Walter

Last Updated: 03/19/2023

Views: 6202

Rating: 5 / 5 (50 voted)

Reviews: 89% of readers found this page helpful

Author information

Name: Carlyn Walter

Birthday: 1996-01-03

Address: Suite 452 40815 Denyse Extensions, Sengermouth, OR 42374

Phone: +8501809515404

Job: Manufacturing Technician

Hobby: Table tennis, Archery, Vacation, Metal detecting, Yo-yoing, Crocheting, Creative writing

Introduction: My name is Carlyn Walter, I am a lively, glamorous, healthy, clean, powerful, calm, combative person who loves writing and wants to share my knowledge and understanding with you.