What is a DNA test for ethnicity?

Written by Ellen Hinkley
6 February 2017

Ethnicity can be defined in many ways and by a wide range of factors. Culture, language, nationality and religion are just a few of the influences that can contribute to your sense of ethnic identity. DNA testing offers another way to help you define your ethnicity, by looking at your genetic ancestry. Even families that have lived in the same place for several generations may have a diverse genetic heritage, and if you were to trace your ancestry back several hundred thousand years, the current thinking is that you’d discover you share the same ancestral origins as all humans, in Sub-Saharan Africa.

This is the ‘Out of Africa’ theory, and it’s reflected in our DNA which shows that we’re all descended from ‘Y chromosomal Adam’ (our earliest common male ancestor) and ‘mitochondrial eve’ (our earliest common female ancestor). Our DNA can also show us the migratory paths that our ancestors took after leaving Africa in the intervening millennia, to get to where they settled in the thousand year period before the era of mass migration circa 1850.

The test that can tell you about your ethnic makeup is called an autosomal DNA analysis – also known as an ethnicity test – and it can reveal the population groups from this thousand year period who have contributed to your ethnic mix. It’s called an autosomal analysis because it looks at your autosomes; these are our non-sex chromosomes and they make up 22 of the 23 pairs of chromosomes that we inherit from our parents.

Unfortunately, as our autosomes can recombine shortly after we’re conceived, it’s not possible to identify which parts of our autosomes came from which parent, so ethnicity testing will give you a combined view of your DNA heritage, that isn’t specific to your mother or father.

If you’d like to explore the ethnicity DNA tests that you can buy online, you can visit our ancestry DNA listings, click the ‘Compare Tests’ button next to the companies we’ve listed, and check out the ‘Autosomal Analysis’ or ‘Autosomal Analysis & Family Finder’ tests.

So what can an ethnicity DNA test actually tell me?

The core feature of all ethnicity DNA tests is to show you a breakdown of the ethnic groups who have contributed to your autosomal DNA, normally as a list, pie chart, and/or map in an online account. It’s understood that these tests give you a picture of your ethnic heritage from the past five to six generations, and this is because the number of your ancestors increases exponentially the further back you go.

We each had two ancestors one generation ago, four ancestors two generations ago, and by the time we’ve gone back five generations, 32 ancestors have each contributed approximately 3% of our autosomal DNA! As an ethnicity test can’t show you how your autosomal segments have been passed from one generation to the next, trying to derive meaningful information about the ethnicities of your ancestors more than five generations ago is virtually impossible.

It’s worth bearing in mind that when you’re presented with the population groups that have contributed to your DNA, some of the groups revealed may be very general (e.g. Western European) and the report may not tell you when or for how long each group was located in the region that it’s named after. The specificity of the population groups depends on the reference populations used by the company you test with (discussed later). Therefore, if a detailed ethnic breakdown is important to you, look for example reports from the company you’re considering, or get in touch with them to ask for a list of the reference populations that they use.

As well as showing you which ethnic groups you’ve inherited your DNA from, autosomal DNA tests can also be used to find living relatives and build your family tree. Many people attempting to build their family tree will often make breakthroughs in their research when they combine a DNA genealogy test (such as an ethnicity test) with traditional genealogical techniques.

Neanderthal and Denisovan DNA
Some ethnicity DNA tests will report on the percentage of your autosomal DNA that can be linked to Neanderthals and/or Denisovans – these are non-human ‘hominin’ species that inter-mixed with humans before dying out tens of thousands of years ago. The percentage of our DNA that originates from hominins is 1-5% and it varies greatly between individuals. Only a few genetic ancestry companies include this analysis in their tests (e.g. 23andMe and National Geographic’s ‘Geno 2.0’) and it can be fun to see how much of these ancient species still live on in your genetic code.

Family Finder Feature
After taking a DNA test for ethnicity, many ancestry companies will give you the option to contact their other customers, providing you share sections of your autosomal DNA with them (meaning that you’re related to these individuals to a greater or lesser degree). The companies that do this maintain ‘Family Finder’ databases, and the people you’re related to are usually referred to as ‘matches’. The three largest companies that do this are Family Tree DNA, Ancestry.com and 23andMe, and as part of the results that they provide, you’ll be able to see a list of these living relatives ranked according to how closely you’re related to them.

It should be said that if these Family Finder tools sound like a good way to add to your family tree, the majority of the matches you’ll be shown will be 3rd cousins or more distant, and it can take a significant amount of research to place them on your tree. That said, if you’re prepared to contact your matches and try to piece together your familial connection, using the Family Finder feature can be lots of fun and a great way to make friends all over the world!

Reference populations

As discussed earlier, in order to determine the ethnicities present in your genetic make-up, genetic ancestry companies can analyse your autosomal DNA to seek out the genetic variants uniquely associated to certain population groups. These groups are known as ‘reference populations’, and they’ve been constructed by sampling the DNA of modern populations around the world, as well as from human remains at various archaeological sites. By identifying these genetic variants in your genetic code, companies can report on the groups that have contributed to your DNA.

Companies differ in terms of which reference populations they use. Some companies will create their own reference populations, while others will use populations identified in published studies. For example, 23andMe produce their own reference populations by sampling their customers (as long as the grandparents of those customers were all born in the same country). They then combine this data with public population data, produced by projects such as the Human Genome Diversity Project.

Most companies will use algorithms to compare the genetic variants uniquely associated to a reference population with those identified in the person being tested. This can help them exclude unlikely population groups from your ethnic mix, and ensure that the ethnic groups you’re shown to be composed of are more accurately reported. Although most companies will share the reference populations they use with their customers, they rarely provide information on the algorithms they’ve developed.

If you’ve taken an ethnicity DNA test with more than one company, then you’ll know that it’s common for the results to differ. This is partly because different companies use different reference populations and/or different algorithms.

The limitations of reference populations
Although reference populations are the primary method by which companies calculate your ethnic mix, they don’t represent actual living populations. Instead, they’re a theoretical group who share a unique set of genetic variants, believed to belong to a distinct ethnic group in the past. This is why an ethnicity DNA test will show you that you’re a mix of different ethnicities, instead of placing you in a single ethnic group.

There are a number of reasons why the vast majority of living humans are a blend of ethnicities. Firstly, from around 1850 onwards, people started to migrate around the world and mix in large numbers. Secondly, as national borders have changed over time, the only clear cut ethnic groups are those that are highly isolated. For example, as individuals have migrated in large numbers between France and Britain in the last few thousand years; those in Northern France exhibit a similar ethnic mix to those in Southern England.

For these reasons, mapping segments of your autosomal DNA to whole continents can be determined with a high level of certainty, but when you try to attribute these segments to specific tribes, regions or even countries, the certainty decreases. This is why some genetic ancestry companies will attribute a proportion of your DNA to areas such as ‘Eastern Europe’ or ‘Southern Asia’, instead of to specific countries.

How much does an ethnicity DNA test cost?

Costs vary depending on the company you buy from. For example, the three most popular DNA ethnicity tests are undertaken by 23andMe, Family Tree DNA (FTDNA) and Ancestry.com. They all analyse autosomal DNA to report on your ethnic mix: 23andMe’s costs £149, FTDNA’s (named the ‘Family Finder’ test) costs £60 and Ancestry.com’s (named ‘AncestryDNA’) costs £79. However, it’s worth bearing in mind that 23andMe’s test also includes a Y DNA analysis and a mitochondrial DNA analysis, so if you’re interested in your paternal and maternal lineage (discussed below), this may be the more cost-effective choice!

How is an ethnicity test different to a Y DNA test or a mitochondrial DNA test?

Although autosomal DNA testing is primarily used to establish your ethnic mix, there are other aspects of your ethnicity that you can explore by testing other types of your DNA. You can trace your paternal lineage back to Y chromosomal Adam using a Y DNA test, and your maternal lineage back to mitochondrial eve by using a mitochondrial DNA test.

These tests can reveal the migratory paths of your paternal and maternal ancestors after they left Africa 200,000 years ago. By studying the migratory route they took, this can help you identify the ethnic groups they may have been part of. That said, as your paternal line is your father’s father’s father etc., and as your maternal line is your mother’s mother’s mother etc.; your paternal and maternal ancestors represent a smaller and smaller proportion of your ancestry the further back you go (just one sixteenth of your total ancestry five generations ago). Therefore, tracing your migratory paths back thousands of years may provide insights, but they’re a poor means of exploring your ethnic mix.

Both men and women can take mitochondrial DNA tests (because we all possess mitochondria in our cells), but it’s worth noting that women are unable to take Y DNA tests as they do not possess a Y chromosome. If you’re female and you’d like to learn more about your paternal lineage, you can ask a close male relative to take a Y DNA test on your behalf – read our article about Y DNA testing for more information.

Paternal and maternal tests can also be used to help you find living relatives, providing the company you purchase the test from offers a Family Finder feature.