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How Many Generations Back is 1% DNA?

Did you get 1% matching a region on your DNA results? In this post, learn how many generations back 1% DNA might be in your family tree.

How Many Generations Back is 1% DNA

The ethnicity estimate shows where in the world your ancestors may have lived within approximately the past 300-500 years, with percentages matching each region. We can usually assume that the higher percentages were inherited from more recent ancestors, and smaller regions from more distant ones.

This is easy enough to understand, of course. Big questions often arise when we see a region on our results that we were not expecting, or a region that shows us matching by a small percentage, like 1%.

We might wonder how far back we would need to look in our family tree to find the ancestor who passed down the 1% to us, and whether it is possible that the 1% showed up by mistake.

How many generations back to 1% DNA ancestor

Generally speaking, we could expect to find the ancestor who passed the 1% ethnicity region to us located about seven generations back in our family tree. This means that the 1% DNA could have come from a great-great-great-great-great grandparent.

This scenario assumes that the percentage of DNA matching the 1% ethnicity region doubles each generation we move back in your family tree. For example, if the 5th great-grandmother was “100%” of the region in question, we would expect her descendants to match each region as follows:

  • you – 1% DNA matching the region
  • your parent – 2% DNA matching that region
  • your grandparent – 4% DNA matching that region
  • your great grandparent – 8% DNA matching the region
  • your great-great grandparent – 16% DNA matching the region
  • your great-great-great grandparent – 32% DNA matching the region
  • your great-great-great-great grandparent – 64% DNA matching the region
  • your 5th great-grandmother – the “100% ancestor”

In reality, DNA inheritance rarely works so predictably. While a child does inherit an equal 50% of each of their parent’s DNA, the portion that they do inherit is randomly selected.

This means that ethnicity regions could be passed down in larger “chunks” than the even 50% that we would expect in a mathematically perfect scenario, or even not passed down at all. When we are considering how far back to look for an ancestor who passed down 1% of an ethnicity region to us, we must keep an open mind and look a little closer, or a little further, in our tree than what the estimates predict.


How to find your 1% DNA ancestor

There are a few strategies you can follow to determine which side of the family you should look for the ancestor matching your 1% region. In addition, there are a few things you can do to help narrow down how far you need to look to find that ancestor.

Ancestry SideView

If you took a DNA test with Ancestry, you can actually automatically see your ethnicity estimate divided by parent. Ancestry’s SideView Ethnicity Inheritance feature assigns our regions to each of our parent using some pretty complex computing.

Asking another relative to test

If you have another relative, especially an older relative, such as a parent, grandparent, aunt or uncle, you can often use their ethnicity estimate to help you isolate branches of your family tree that need more research. For example, if you test both of your grandparents and one of them also has that region, this is a clue that this grandparents’ ancestors were likely the source of the DNA matching that part of the world.

Compare ethnicity regions with DNA matches

If your 1% DNA was passed down from someone living in that region of the world not long ago, you might have luck exploring your 3rd-4th cousin DNA matches for the purpose of comparing your ethnicity estimates.

You can compare your ethnicity estimate with most of your DNA matches on Ancestry and 23andMe. Some testing companies also allow you to filter and sort your matches to only display those matches who show a particular region on their results.

If you find a DNA match that shares the region, especially if they have a much larger percentage matching the area than you do, you could explore your shared DNA matches to see if you can find a pattern.

It is important to mention that our DNA matches are related to us through a variety of different ancestors from our family tree. They may have inherited DNA matching the same region as you from someone who is not related to you at all.

Try chromosome painting with ethnicity added

A more advanced method for tracing smaller regions, such as 1% regions, would is chromosome painting. This method involves identifying the common ancestor shared between you and your DNA matches, and then overlaying ethnicity data corresponding with your DNA segments, which can be obtained from your 23andMe results.

The best website for keeping track of chromosome mapping and painting efforts is DNA Painter, which is free to use.

Could 1% DNA ethnicity region to be from a recent ancestor?

We inherited all of the regions on our ethnicity estimate, including the 1% regions, from our recent ancestors. If your DNA results are correct (more on this below), you could have inherited DNA matching this region from one or both of your parents.

If you do have ancestors who shared a genetic heritage with people from your 1% region, then at least one of your parents should also show DNA matching that region. As I mentioned before, DNA matching the regions on our ethnicity estimate is not passed down in equal portions, so your parent might also show 1%, or have much more than the 2% we could expect to see.

Is 1% of an ethnicity region ever a mistake?

Yes, it is possible that a region on our ethnicity estimate is incorrect. There is a bigger chance of this happening with a smaller percentage, such as those regions that show up as only matching our DNA at 1%.

How does this happen?

The DNA testing company’s software has a very complex algorithm that compares our DNA to reference panels made up of DNA samples obtained from many thousands, sometimes tens of thousands, of people around the world.

The DNA of any two humans, regardless of their ancestral background, is almost 100% identical, which means that the software is looking for exceptionally small differences to isolate our ethnicity regions. It is easy for a very small DNA segment to be “misidentified” as a neighboring region, which is the most common result of this “error”.

Most of the time, however, our DNA results are pretty accurate. So, it’s always worth exploring your 1% regions.

Many people have been able to ask their parents to take a DNA test, and sometimes their parents do not show the same 1% regions (or other small percentages). If this happens, we should not automatically assume that this means our 1% region is incorrect, since it could be our parent’s DNA that the algorithm has misinterpreted.

Conclusion

I hope that this post has helped you understand more about what it means to show 1% of your DNA matching a region of the world on your ethnicity estimate. While it can sometimes be in error, it typically means that you had an ancestor who had a genetic connection to that area.

If you have any questions about something that you read in this post, or if you would like to share the regions that show up as “1% regions” for you on your DNA results, please join in the discussion below.

Thank you for reading today!

Share the knowledge!

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H K

Friday 18th of November 2022

I like to focus on matches that may or may not support those ethnicity estimates. I uploaded 3 different tests to MyHeritage and then later tested directly there. Each time, they estimate that I have a small amount of West Asian. My Ancestry kit gets 3%, all the other kits show between 1-2% West Asian only. At other sites, I get NO West Asian. Instead I get some Ashkenazi Jewish at 23andMe, (through a few updates)... and some Magyar at FTDNA (after their last update). I get nothing remotely related at Ancestry. Matches... always someone fully Jewish by ethnicity, at all sites. I think that's the actual source... somehow.

H K

Friday 18th of November 2022

@H K, By the way, I also get trace South Asian/Sri Lankan at 23andMe... no relevant matches. (I sometimes wonder if this is possibly connected to Sephardic Jewish ancestry. After all, there is an Indian city on the western coast that had a lot of Portuguese traders coming and going... or maybe not quite going... several centuries back. Who knows? Pure speculation at this point.)

Tricia Javier

Saturday 12th of November 2022

I have 1.3% Irish, Scottish and Welsh in my DNA results through MyHeritage. I’m from Philippines and I am aware of how many foreigners intended to colonised the country. I admit that I was surprised though because I always anticipated that I should have more Spanish ancestry because in my maternal side she has so many closed cousins who have Spanish roots. However, to gain stronger evidence, I have to study my DNA matches with the same ethnicity as mine and it turns out that I have some matches who have high percentage of the mentioned ethnicity which is not definitely false positive. Moreover, I used GEDmatch MDLP. I understand that the calculators are no longer updated but it gives me lots of proof that I have North or West European ancestry or WHG in each MDLP which I conclude that I have roots in Celtic regions and that it is not just ‘incorrect’ or ‘false positive.’

Tricia Javier

Saturday 12th of November 2022

@Tricia Javier, moreover, I used all of the MDLP calculators and the results are mostly equal.

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