This article gives simple and clear explanations of the second cousin relationship.
I also answer as many questions around second cousins as I can think of. Let’s start with the basics!
What Is A Second Cousin?
Your second cousins are the children of your parents’ first cousins. You share great-grandparents with your second cousins.
Here is an illustration of the relationship:
You are both three generations away from your common ancestors. One of your grandparents is a sibling of a grandparent of your second cousin.
Difference With Other Cousins Relationships
Second cousins are more distantly related than first cousins.
You probably understand what a first cousin is. But if you’d like to see similar diagrams, check out our article that explains first cousins – it answers a lot of questions.
But let’s focus on other relationships that can be confused with second cousins.
First of all, a second cousin is different from a first cousin once removed. To get a clear picture of why, check out our article that explains first cousins once removed.
Secondly, second cousins are closer than third cousins. Your child is a third cousin to the child of your second cousin. We have a separate article that explains third cousins.
But what about second cousins once removed? Let’s look at that next.
Second Cousin Versus Second Cousin Once Removed
People do get confused between these two relationships.
What does “once removed” mean, anyway?
When your second cousins are “once removed”, this means that they are one generation away from you.
This can be either up a generation (your parents’ generation) or down a generation (your children’s generation).
Children of your second cousins
Probably the easiest to understand are the children of your second cousins. These children are your second cousins once removed.
This illustration shows a family tree with the “once removed” relationship marked.
Your parents’ second cousins
We’ve looked at the relationship when the removed is down a generation.
But what if it’s up a generation at your parents’ level? It’s not the parents of your second cousins. Those are your first cousins once removed.
We need to move out further in the family tree and go back as far as your great-great-grandparents.
The second cousins of your parents are your second cousins once removed.
This infographic highlights the relationship:
What does 2C1R mean?
You may see articles or charts referring to 2C1R.
2C1R stands for second cousin once removed.
Are Second Cousins Blood Related?
Your second cousins are blood relatives because you share common ancestors i.e. two of your great-grandparents.
However, if the cousin relationship is through marriage, then you are not blood relatives.
When you’re introducing the spouse of a second cousin to people, you probably refer to him or as your cousin. But this is not a blood relationship.
In the diagrams above, we only show your blood relatives.
Do Second Cousins Share DNA?
Second cousins share amounts of DNA ranging from about 2.9% to 5%. The average percentage of shared DNA is about 3.1%.
The number of reported shared centimorgans range from 41 to 592 cM. The average is about 229 cM.
The reason for the variability is that people inherit different amounts of DNA from common ancestors. DNA gets shuffled, separated, and recombined as it passes down through generations.
You may receive chromosomes from your great-grandparents that your cousins don’t get – and vice versa.
The amount passed down from your great-grandparents also gets smaller with each generation.
Using DNA websites
If you’ve used one of the big commercial DNA testing services, you may be researching a list of DNA relatives who also tested with the same company.
The websites like Ancestry and 23andMe will give you a prediction of relationships based on the amount of shared DNA.
Be aware that the higher end of the range for second cousins will overlap with the lower end of a first cousin. So don’t assume that the labels are correct.
Can second cousins not share DNA?
I mentioned that the DNA from an ancestor gets reduced as it passes through generations.
Is it possible that you don’t share any DNA with a second cousin? The answer is no.
A researcher at Cambridge University, Kevin Donnelly, conducted a study into the probabilities that people don’t share DNA with family members.
This showed that second cousins will always share some DNA.
However, that is not the case with second cousins once removed. But the possibility is a tiny 0.1% (that’s a tenth of one percent).
How Many Second Cousins Could You Have?
Birth rates in your country and community play a big part in predicting the number of second cousins.
I wrote an article on using birth rates to calculate the numbers for the U.S., the UK, and Ireland. These were the results based on the 2013 statistics:
- United States: 18 second cousins
- United Kingdom: 13 second cousins
- Ireland: 16 second cousins
I suspect that the U.S. number may vary widely between communities and income levels in the country.
If you can find more local birth rate stats or you’re from another country, just follow this article where I calculate the number of cousins Irish people have. You can work out your own predictions.
How Are Second Cousins Categorized?
Are second cousins part of close family? Extended family? Distant family?
This depends on the context. I’ll look at this from a legal context, a genetic context, and normal conversations.
In many jurisdictions, second cousins are seldom considered immediate family in legal matters.
For example, if your employment has restrictions that mention immediate family then this may not include second cousins.
However, you should always check with the specific department (or state authority).
You’re wondering why you didn’t get a wedding invitation, and the answer is that only “close family” were invited. What does that mean?
You see “close family only” on a funeral notice. Should you attend?
This depends on the culture and community. But second cousins would be considered outside of “close family” in my Irish culture.
If you’re not sure, ask older generations in your family.
If you’ve tested with a commercial DNA site, you may be researching your DNA relatives. Some of the websites put a label of “close family” on some people in your list of relatives.
For example, Ancestry.com includes two of my second cousins in their close family category. You can read more in this section on Ancestry’s relationship labels.
But don’t assume that people labeled as “Distant Family” aren’t second cousins or second cousins once removed. Pay particular attention to the top relatives in the “distant” list.
You may simply be on the lower end of shared DNA with these relatives.
Can You Marry Your Second Cousin?
Every state in the U.S. allows marriage between second cousins.
Depending on the state, it’s important to be sure that your relationship is as second cousins and not first cousins once removed. Six states prohibit the latter marriages.
We have more details in our article on first cousins once removed.
Outside the U.S.
It may surprise you to learn that the United States is somewhat unusual in having any restrictions on cousin marriages.
Many regions have no restrictions at all. Marriage between second cousins is allowed in most countries.
Can Second Cousins Get Married In A Catholic Church?
Even though it may be perfectly legal to marry your second cousin, there are other hurdles if you want to a Roman Catholic wedding.
In general, the Catholic Church isn’t keen on first cousin marriages. But is okay in the present day with second cousins.
Up until 1983, second cousins were not allowed to get married in a Catholic church. They could only have a civil marriage.
Since the introduction of the 1983 Code of Canon Law, second cousins can marry in a Catholic ceremony.
Canon law and second cousins
Canon law is based on counting the number of generations away from the common ancestors for the two potential spouses.
The common ancestors of you and your future spouse are your great-grandparents.
You are both three generations away from your great-grandparents. We add those numbers together to come up with six degrees.
This is called six degrees of “consanguinity” – but don’t get too caught up with the terminology.
The point is that Canon Law used to prohibit marriages up to the sixth degree. This was relaxed to the fourth degree (first cousins).
Second cousins have no restrictions.
Frequently Asked Questions
Do second cousins share the same blood?
Second cousins are blood-related and are considered to share the same blood as their common ancestors.
If you want to know how much DNA they share, check out an earlier section in this article.
What is my second cousin’s child to me?
Your second cousin’s child is your second cousin once removed.
Check out the earlier section in this article about generations removed.
What are my second cousin’s parents to me?
Your second cousin’s parents are your first cousins once removed.
Check out the diagrams in the earlier sections of this article.
Are second cousins extended family?
Most western cultures consider second cousins to be part of extended family.
As second cousins share great-grandparents, older generations of families usually understand the exact connection and family relationship.