What Is A Ninth Cousin? (Explained)

Navigating the vast web of distant familial relationships can be a fascinating journey into your ancestry.

One of these distant connections is your ninth cousin.

You’re probably familiar with terms like first, second, third, fourth, and fifth cousins. However, what might not be commonly understood is that the concept of ‘cousinhood’ extends indefinitely across generations. In theory, for every generation that exists, there’s a corresponding cousin relationship that can be identified.

This term might seem complex, but in reality, it’s a clear marker on the tree of your family’s past. In this post, we’ll delve into the definition of a ninth cousin, explore the concept of ‘once removed’ and ‘twice removed’, understand the degrees of separation, and discuss the chances of shared DNA.

We’ll also provide a guide to help you locate your ninth cousins.

Whether you’re a novice genealogist or an experienced family historian, this exploration of the intricate ties that make up your family tree will provide a wealth of insights into your heritage.

You may have already signed up to a family history research service like AncestryDNA or 23andMe and have found quite a few family matches already.

Understanding The Concept of a Ninth Cousin

A “9th cousin” refers to a person who shares a common ancestor with you 10 generations ago, specifically, your 8-times-great-grandparents.

Put simply, your parents are 1 generation away, your grandparents 2 generations away, and so on up to 10 generations away for your 9th cousins.

While you share a family connection, it’s worth noting that such distant relatives typically share a very small amount of common DNA due to the many generations that separate you.

This term is a key piece of the expansive puzzle that forms your genealogical heritage.

‘Once Removed’ and ‘Twice Removed’ in the Context of 9th Cousins

The terms “once removed” and “twice removed” denote a difference in generations in your cousin relationships.

If someone is your 9th cousin once removed, this means that there is a one-generation difference between you and your 9th cousin.

9th Cousin Once Removed

The child of your 9th cousin is your 9th cousin once removed, because there is a one-generation difference between you and the child. Conversely, if the 9th cousin is from your parent’s generation, they would also be your 9th cousin once removed.

9th Cousin Twice Removed

A 9th cousin twice removed indicates a two-generation difference. So, your 9th cousin’s grandchild or your grandparent’s 9th cousin would be your 9th cousin twice removed.

In essence, these terms help denote the exact generational distance between relatives, making the complex web of distant familial relationships a bit clearer.

The Degrees of Separation Between Ninth Cousins

In genealogy, the “degrees of separation” between two people typically refers to the number of steps or individuals linking them in the family tree.

In the case of ninth cousins, this would be the number of generations between you and your shared common ancestor, plus the number of generations between your ninth cousin and the same common ancestor.

For ninth cousins, you both are ten generations removed from your common ancestors – your 8-times-great-grandparents. Hence, the degrees of separation would be 20.

This includes the 10 generations from you to your 8-times-great-grandparents and the 10 generations from your ninth cousin to the same 8-times-great-grandparents.

Therefore, ninth cousins have 20 degrees of separation in the family lineage.

How Many 9th Cousins Do We Have?

Estimating the exact number of your 9th cousins is tricky as it heavily depends on various factors, such as the size of each generation in your family, the number of children each pair of ancestors had, and the number of those children who successfully had their own children, the country you live in and so on.

However, under the assumption that each couple in your ancestry had about 2-3 children who lived to reproduce, the number of 9th cousins could potentially reach into the millions!

To illustrate this, let’s imagine that each of your ancestors had 3 children who lived to adulthood and had their own children.

Following this pattern, by the time you reach the level of your 8-times-great-grandparents, you’d have about 8,192 ancestors (3^10 = 59,049 divided by 2 for each side of your family).

Considering this, each of those ancestors would potentially have a similar number of descendants, leading to a very large number of potential 9th cousins.

Keep in mind, this is a very simplified estimate and the real numbers could be lower or higher depending on the actual birth, survival, and reproduction rates in your family’s history.

It’s also important to note that due to intermarriages between distant relatives, the same individual might appear in your family tree in more than one place, which can also affect the count.

Are 9th Cousins Blood Related?

Ninth cousins are not blood related. Although you share common 8th great-grandparents, the amount of DNA shared at this level of relation is usually extremely small, often less than 0.01%.

In fact, it’s possible for 9th cousins to share no detectable DNA at all, due to the randomness of DNA inheritance. Even though the genetic connection is tenuous, genealogists often value these relationships for the historical and geographical insights they can provide.

In genealogy, the terms close, extended, and distant are used to describe the degrees of relation among family members.

1. Close Relatives: These are your immediate family members and the ones with whom you share a significant portion of your genetic makeup. It includes your parents, siblings, children, and grandchildren.
2. Extended Relatives: These are relatives beyond your immediate circle but still share a noticeable amount of genetic material with you. It includes aunts, uncles, nieces, nephews, first cousins, and grandparents.
3. Distant Relatives: These are family members with whom you share a smaller amount of genetic material due to the number of generations that separate you. It starts from second cousins and goes further to include third cousins, fourth cousins, and so on. The term is also used to refer to ‘removed’ relatives – for example, a cousin ‘once removed’ would be the child of your first cousin.

These distinctions help genealogists understand and communicate the familial relationship and also have implications for the potential amount of shared DNA between relatives.

Ninth cousins sit well and truly in the “distant relative” classification.

Other Types of Ninth Cousins

Ninth cousins can also be referred to by other names that indicate some variation in their biological connection. Below are some variations of the term “ninth cousins”.

Ninth Cousin Once Removed

“9th cousin once removed” means the person is either one generation above or below you, sharing the same 8th great-grandparents.

If they’re one generation above, they’re your 9th cousin’s child. If one generation below, they’re the 9th cousin of your parents. The “once removed” signifies a one-generation difference.

Ninth Cousin Twice Removed

“9th cousin twice removed” refers to a relationship with a two-generation difference, based on shared 8th great-grandparents. If they are two generations above you, they are the grandchild of your 9th cousin. If they’re two generations below, they are the 9th cousin of your grandparents. The “twice removed” indicates a two-generation gap.

Half Ninth Cousin

A “Half 9th Cousin” shares only one common 8th great-grandparent with you instead of the pair. This typically occurs when one of your ancestors had children with more than one partner. Despite this half-relationship, you and your half 9th cousin are still part of the same extended family network.

Famous Ninth Cousins

The most famous and unlikely ninth cousins is Barrack Obama and Brad Pit.

Edwin Hickman, who passed away in Virginia in 1769, serves as the link between Obama and Pitt. Obama’s white Kansas-born mother, Ann Dunham Sutoro, is a direct descendant of Hickman’s son James.

Hickman’s other son, Edwin Jr, James’s brother, is head of the line leading to Brad Pitt.

The Probability of Shared DNA Among Ninth Cousins

The probability of sharing detectable DNA with a 9th cousin is very very low.

When you are born, you inherit 50% of your DNA from each parent. With each successive generation, the amount of DNA that you share with your ancestors decreases approximately by half.

So, for instance, you share about 12.5% of your DNA with a first cousin.

By the time you get to the level of 9th cousins, the percentage of shared DNA drops to a minuscule amount. In fact, it’s so low that most commercial DNA tests would not reliably be able to identify such a distant cousin relationship.

To give you an idea, consider that full third cousins (sharing great-great-grandparents) only share an average of about 0.78% of their DNA, and even this amount is detectable only about 90% of the time.

By the time you get to fourth cousins (sharing 3x-great-grandparents), the DNA overlap drops to about 0.20%, detectable about 50% of the time. For fifth cousins (sharing 4x-great-grandparents), the average shared DNA drops to 0.05%, detectable less than 15% of the time.

Given these figures, you can see how the shared DNA between ninth cousins (sharing 8x-great-grandparents) would be nearly negligible and usually undetectable with current DNA testing technologies.

However, this doesn’t mean you definitely share no DNA with a 9th cousin, just that any shared DNA is likely to be such a small fraction of your total DNA that it would be hard to differentiate from the background noise in a DNA test.

Genealogical Relationship	Probability of No detectible DNA Relationship
1st cousin	0.00%
1st cousin once removed	0.00%
1st cousin twice removed	0.00%
2nd cousin	0.00%
2nd cousin once removed	0.10%
2nd cousin twice removed	2.3%
3rd cousin	2.3%
3rd cousin once removed	12.10%
3rd cousin twice removed	30.70%
4th cousin	30.70%
4th cousin once removed	52%
4th cousin twice removed	69.8%
5th cousin	69.8%
5th cousin once removed	82.2%
5th cousin twice removed	89.9%
6th cousin	89.9%
6th cousin once removed	94.4%

How To Find Your 9th Cousins – A Short Guide to Locating Your Distant Relatives

Finding your 9th cousins can be a challenging yet rewarding journey through your family’s history. Here’s a brief guide on how to begin:

1. Start with What You Know: Compile as much information as you can about your family tree. Gather names, birth dates, and locations from family members, vital records, or family documents. This will provide a solid starting point.

2. Use Genealogical Databases: Websites like Ancestry, MyHeritage, and FamilySearch have extensive databases and can help build out your family tree. They offer historical records and user-created family trees which may connect with your lineage.

3. DNA Testing: Consider taking a DNA test from companies like AncestryDNA or 23andMe. These tests often connect you to a database of others who have taken the test and share some amount of DNA with you, potentially including distant cousins. Note that 9th cousins may not be reliably identified through shared DNA due to the minute amount of shared DNA.

Autosomal DNA testing is a popular tool for genealogy. This type of test looks at the 22 pairs of non-sex chromosomes that you inherited from both your parents. Because these autosomes are a mix of both parents’ DNA, they can trace lineage from both sides of your family, making it a useful tool for connecting with a broad range of relatives.

To take an autosomal DNA test, you’ll typically need to do the following:

Choose a Testing Company: There are several companies that offer autosomal DNA testing services, such as AncestryDNA, 23andMe, MyHeritage DNA, and FamilyTreeDNA. Each has its strengths and weaknesses, so you might want to do a bit of research to decide which is best for your needs.

Purchase a Test Kit: Once you’ve chosen a company, you can order a test kit from their website. The kit will include everything you need to collect a DNA sample at home.

Collect and Submit Your DNA Sample: Most kits require either a saliva sample or a cheek swab. After you’ve collected your sample, you’ll package it up as instructed and mail it back to the company.

Wait for Results: The company will extract and analyze your DNA from the sample you sent. This process can take several weeks. Once your results are ready, you’ll be able to view them online. The company’s website will usually provide a variety of tools for exploring your genetic ancestry and connecting with relatives who have also taken the test.

Remember that while these tests can provide fascinating insights into your ancestry, they should be taken with a grain of salt. The science of genetic genealogy is still evolving, and results should be considered as one piece of the larger puzzle of your family history.

4. Join Genealogical Societies: Local, regional, and nationality-based genealogical societies often have resources and connections that can help you in your search.

5. Hire a Professional: If your search becomes too daunting or you hit a dead-end, consider hiring a professional genealogist. They have the expertise and resources to uncover connections that may be hard to find on your own.

Remember, patience and persistence are key. Happy hunting!

Quick Cousin Relation Reference List

See how you are related to your cousins

• first cousins share grandparents
• second cousins share great-grandparents
• third cousins share great-great grandparents (2 greats)
• fourth cousins share great-great-great grandparents (3 greats)
• fifth cousins share great-great-great-great-great grandparents (4 greats)
• sixth cousins share great-great-great-great-great grandparents (5 greats)
• seventh cousins share great-great-great-great-great-great grandparents (6 greats)
• eighth cousins share great-great-great-great-great-great-great grandparents (7 greats)
• ninth cousins share great-great-great-great-great-great-great-great grandparents (8 greats)
• tenth cousins share great-great-great-great-great-great-great-great-great grandparents (9 greats)

Other Types Of Cousins In Your Family Tree

Second Cousins
Third Cousins
Fourth Cousins
Fifth Cousins
Sixth Cousins
Seventh Cousins
Eighth Cousins
Ninth Cousins
Great Cousins