What is a Second Cousin DNA Match?

What is a second cousin DNA match? Are second cousin DNA matches always true second cousins?

In this post, you’ll learn what type of relationships might fall into the second cousin DNA match category, and how to figure out how your match might be related to you.

The information you learn in this article will help you understand more about your second cousin DNA match no matter which company you tested with.

What does it mean to have a second cousin DNA match?

Each DNA testing company uses their own standards to determine an estimate for how you are related to a particular DNA match. 

Generally, the total amount of shared DNA, the number of DNA segments shared, and the length of the largest DNA segment are the major factors that help the software decide which category a DNA match should be placed in. 

A second cousin DNA match can be an actual second cousin

This estimated relationship is nothing more than an estimate, however.

What this means that the person who is in the second cousin category on your match may be a second cousin, slightly more closely related, or slightly more distantly related, but they share the amount of DNA with you that falls within the range of a second cousin match.

Second cousin is the estimated relationship for a DNA match

A person who falls into the second cousin category is generally related to you by an order of several degrees (Ancestry uses a range of 4-7 degrees for the second cousin category.  In order to count degrees of separation, you count from yourself up to the common ancestor, and down the line to your relative. 

For example…

Your grandparents are separated from you by two degrees, and your first cousins by four degrees, for example.  An actual second cousin, with who you share a great-grandparent, is separated from you by six degrees, since you have to count up to three to get to your great-grandparent, and then down to your second cousin (three more degrees), for a total of six.

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What relationship is a second cousin DNA match?

Many people find a few second cousin DNA matches on their list and wonder about their shared connection.

It appears as if Ancestry places matches into the second cousin category if they have somewhere between 200-700 centimorgans of shared DNA.  This is an approximate estimate, based on kits that I manage.

As I mentioned before, each company has a different method for determining which DNA matches show up as “second cousins” to you. The thresholds will be similar no matter which company you used to test, however.

On one hand, this wide range of shared DNA is great – your second cousin match could be related to you in many different ways.  This means that they might be an actual second cousin, or they might have some other relationship to you.

On the other hand, your DNA match could be related to you in many different ways, so you’ll have to do some detective work to figure out exactly who your match is to you.

The good news is that we almost always learn something new about our family by learning exactly how our second cousin DNA matches are related.

Most common relationships within the 200-700 shared centimorgans:

A true second cousin will typically share as little as 75 cMs (this is “centimorgans” abbreviated), as as many as 360 cMs, according to one set of experts. Blaine Bettinger has put together an excellent chart with user-submitted data that reports that second cousins can share between 46-515 cMs.

This range of shared DNA overlaps with more than one dozen other genealogical relationships.

Below is a list of most of the other possible relationships that a second cousin DNA match may have with you, based on the amount of shared DNA:

  • First cousins (usually share above 700, and as high as 1200, but can occasionally share as little as 520-540)
  • First cousins once-removed
  • Half-first cousins
  • Second cousins
  • Half-second cousins
  • Second-cousins once-removed
  • Third cousins (usually share less than 200, but can occasionally share slightly more)
  • Great aunt or Great uncle
  • Great-great aunt or uncle
  • Half-aunt or half-uncle
  • Half-great-aunt or uncle
  • Half-great-great aunt or uncle
  • Half-great nephew or niece
  • Half-great-great nephew or niece

I might have missed a relationship or two in this list, but I am sure that you now understand my point.  A second cousin match on your DNA list is actually quite exciting. 

It could be any of the above relationships, and it will take some detective work on your part to figure out the actual path to your common ancestor.

How are you related to your second cousin DNA match?

My mom just got a brand-new second cousin match today (see image below), which inspired me to write this post.  I don’t know how this match is related – yet – but I’ll walk you through my thought process with the idea that you can use what you learn here on your own DNA match list.

What does a second cousin match look like on Ancestry DNA
This image shows shared matches between second cousin DNA matches on Ancestry

The following are the items that I will check for on the “match profile” (the screen that shows up when I click on his name):

Note: You can see my complete list of how to figure out how a DNA match is connected in this post: How is your DNA match related? Here’s a checklist

Locate your DNA match’s name to learn more information

If my DNA match’s name sounds familiar, even if it is only the last name, that could be a clue.  A second cousin with the same surname as a line in my family is very likely to be related on that line, even if there is a small chance that he coincidentally has the same last name as another line of my family.

How much DNA do you share with second cousin DNA match?

You can see in the image above that my mom shares 249 centimorgans with her match.  This is important information, because it eliminates some of the relationship possibilities that I listed above in the previous section. 

For example, sharing only 248 centimorgans means that they cannot possibly be full first cousins, first cousins once-removed, and it would be highly unlikely that they are half-first cousins.  He can’t be her half-uncle, either, since they don’t share enough DNA for that relationship. 

They also share too much DNA to likely be third cousins, though if there is endogamy in your family, it’s possible to share slightly more DNA with a particular relative from those lines.

These are the relationship possibilities that I am left with:

  • Second cousins
  • Half-second cousins
  • Second-cousins once-removed
  • Great aunt or Great uncle
  • Great-great aunt or uncle
  • Half-great-aunt or uncle
  • Half-great-great aunt or uncle
  • Half-great nephew or niece
  • Half-great-great nephew or niece

The age of DNA match can eliminate relationship possibilities

My mom is in her 60s.  (Sorry, mom!)

I clicked on my DNA match’s name to visit his Ancestry profile, and it says that he is less than 50 years old.  I’m feeling good about eliminating the possibility that he is a half-great-great aunt or uncle, or a great-great uncle.  I also feel like he can’t be her great-uncle, half-great uncle, great-great-uncle, or half-great-great uncle. 

If I eventually found information that proved otherwise, I might keep my mind open to these options.  For now, I think it’s easier to eliminate.

I’ve now reduced my relationship possibility list to the following:

This is really helpful, because it means that I should be looking at my mother’s great-grandparents for a common ancestor.  She has eight great-grandparents, however. 

How do I know which great-grandparent, or set of great-grandparents, I should be looking at for my connection to this match?

Use matches shared in common to find relationship with second cousin match

On Ancestry, they have a cool feature called “Shared Matches“.  Don’t worry if you didn’t test with Ancestry, though, since Family Tree DNA will show you matches that you have in common with someone, and so will My Heritage

This is very helpful when trying to find out how a second cousin is related, especially if you already know how some of your other DNA matches are related to you.

When I look at the matches that my mom shares with my new DNA match, I can see that all of her shared matches are either me, my siblings, my mom’s siblings, or people who are descended from my mother’s German great-grandparents.

Compare family tree information with second cousin match

Sadly, this particular DNA match does not have a family tree posted on Ancestry.  I might do a quick Google search with his name and genealogy after it to see if maybe he has posted a public family tree somewhere else.

No family tree? Contact your second cousin match

Based on this information, I can’t further eliminate any relationship possibilities, but now I can contact my mom’s DNA match and explain to him that I believe that he and my mother are connected through these German great-grandparents. 

I’ll write a polite message and include details of who our common ancestors might be, and I’ll ask him if he would like to correspond about our connection.

What if your second cousin DNA match doesn’t respond?

Since a second cousin match is pretty closely related, I might still be able to find out our connection by making sure that I have included all of the children of my mom’s great-grandparents in my tree, and have researched all of their grandchildren, and know the names of all of the spouses of their grandchildren.

This strategy is called “building your tree wide“. If I do this, I bet I will find someone with the surname of my second cousin DNA match.


I hope that this post has given you some ideas about how what a second cousin match is, and how you might be related to a particular second cousin match. 

If you have any questions about something that you read here, please feel free to leave me a comment below.  I look forward to hearing from you.

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