If you did a DNA test expecting to find more Irish, or at least some Irish, represented in your ethnicity results, you are not alone. Many people are surprised to find Irish, and others are surprised not to find Irish in their DNA. With St. Patrick’s Day coming up in just a few weeks, you might be asking if you can still be Irish even though you have none in your DNA results. And if you can be Irish – without showing an ounce of Irish in your DNA – how can you know how Irish you really are?
In my own family, we found ourselves asking ourselves this exact question. Before I did my DNA test, I was expecting to see between 12-15% Irish DNA, at minimum, based on the little information I had about my family’s history. When I got my results back, I only showed 9% Irish DNA. It really got me thinking about these ethnicity estimates, and whether or not we should let our DNA results dictate how Irish (or any other nationality or ethnicity) someone feels like they are.
You are reading this article to help determine how Irish you might be, even if your DNA results don’t show much Irish, or any at all. I have some clues, however, that just might make you feel better about putting on your “Kiss Me, I’m Irish” t-shirt this year. In this post, I’ll give you some pointers to help get you started in finding the truth about your family’s ancestry.
Your Irish ethnicity, or lack thereof, is only an estimate
There are a few tricky things going on when it comes to ethnicity estimates, and the way that ethnicity is inherited. The further back your Irish ancestors were, the bigger the effect these ethnicity inheritance facts will have on you. Keep reading to learn more about why your estimate is only truly an estimate and can never be a complete, detailed report about your ancestry.
We don’t share DNA with all of our Irish ancestors
We have 2 parents, 4 grandparents, 8 great-grandparents, 16 great-great grandparents, 32 great-great-great grandparents, 64 great-great-great-great grandparents, and 128 great-great-great-great-great grandparents. Do you see a pattern here? If you go back only seven generations in your family tree (to the 5th great-grandparent), you have 128 ancestors. What is the reason for this? Your genome is not long enough to “fit” DNA from all of these ancestors.
This means that if even if you have 3 or 4 Irish 5th great-grandparents, it’s possible that you would share absolutely no DNA with them. If they were alive today (oh how I wish I could meet some of my 5th great-grandparents!), you will not share genetic material with all of your 5th great-grandparents. In fact, it is statically possible to share no DNA with a great-great grandparent, though not probable. As you go back further, generation by generation, the probability that you inherited no DNA from a particular ancestor increases.
Additionally, even if you do happen to share DNA with a great number of your distant ancestors, you will only share small amounts. This is important to remember for those of us who were expecting to see larger percentages of Irish DNA in our results.
Ethnicity is not passed down in equal segments
A common misconception when it comes to ethnicity inheritance is that a child inherits 50% of someone’s ethnicity, a grandchild 25%, a great-grandchild 12.5%, and a great-great grandchild 6.25%. While this can certainly happen, it isn’t how it usually happens. Generally speaking, ethnicity is inherited in a process like this example:
- Imagine that your parents each have a basket of colored marbles (each parent has 100 marbles). You will take 50% (exactly 50) of the marbles out of each basket. Your genome can only fit 100 marbles, total. That’s why you can’t have all of the marbles from each of your parents – there just isn’t enough room.
- If you decide to have a child, your child will take 50% of your marbles, and 50% of the marbles belonging to your spouse. Fortunately, no one loses all of their marbles during this process, though parenting can certainly make us feel like this has happened 😉
- If you ever become a grandparent, your grandchildren will inherit 50% of their marbles from your child, and 50% of their marbles from their other parent
- Your great-grandchild will inherit 50% of their marbles from their parent (your grandchild) and 50% of their marbles from their other parent
Do you notice how each generation, 50% of the marbles are not inherited? If your parents are the “original” ancestors in this example, they will still share DNA with your great-grandchild, but not very much. This is because of probability. DNA inheritance is random, and while there is a 100% chance that a child will share 50% of their DNA with each parent, as the generations pass and the original ancestors become more distant, there are simply too many marbles to choose from. Eventually, “the odds” win, and a child will randomly not inherit DNA from an ancestor – in our case, they will not inherit Irish DNA. From that point on, no more DNA from those “original” ancestors will be passed down to future generations, including the Irish ethnicity and DNA segments that they might have shared with other descendants of those same ancestors.
Below is a simplified visualization of how ethnicity is passed down, no matter which ethnicity we are wondering about. In a real-world example, DNA would not be passed down in segments as large as intact as the ones you see below. The DNA in the blue square is the DNA inherited from Grandma, and the colored DNA that is not in a square is from Grandpa. You can see how the grandchildren (Nicole and James) share a much smaller amount of DNA with Grandma and Grandpa than Mike and Sam do. This effect is more pronounced as more generations pass. Eventually, the descendants of Nicole and James would no longer share DNA with Grandpa and Grandma.
Your ancestors might not have been as Irish as you think they were
The final reason that you might not have inherited the Irish DNA that you were expecting is because your Irish ancestors might not have been as Irish as you think they were. Even though Ireland is an island nation, it’s actually pretty close to many other countries, from a geographic, economic, and cultural standpoint. Ireland has Spain to the south, Scotland, Wales, and England to the east, and Iceland to the north. There is a good chance that your Irish ancestor was not “100%” Irish, and if this was the case, especially considering what you now know about how ethnicity is passed down, it should not be a surprise to show less Irish ethnicity than expected.
So, if my DNA can’t tell me how Irish I really am, how can I figure it out?
It’s possible to get an estimate on how Irish you really are, but it might take a little bit of research on your part. You are going to have to figure out where all of your great-great grandparents were born (or great-great-great grandparents, if you really want to get really wild and crazy) and then use the chart below to see how Irish you are.
But I don’t know how many Irish ancestors I have!
If you don’t know where all of your great-great grandparents were born, then the easiest thing to do is build a small family tree on Ancestry. You can build your tree for free and get access to really cool records that make it very easy to research your family tree right from the comfort of your living room. I secretly hope that you will love building your family tree and turn it into a new-found hobby, but it’s okay if you are only interested in figuring out how Irish you are.
If you want to get a two week free trial, you can use the link below (I do get a small commission at absolutely no extra cost to you if you end up keeping your subscription after the free trial is over):
I hope that this post helped you understand a little bit about how you can totally still be Irish, even though you don’t have any showing up in your DNA results. If you have any questions, comments, or would like to share your experience about how you found out that you are Irish, I would love to hear from you below.
Thanks for stopping by!