DNA For Genealogy: Choosing The Best Genealogy Test

Over 12 million people have had their DNA tested for genealogical purposes, according to industry estimates. If you or someone you know is thinking of joining them, or taking a further test with a different company, you may be wondering which test is best and which testing company you should choose.

To help you answer those questions, here’s a quick guide to:
* What tests are available,
* How they might help you grow your family tree or solve those niggling genealogical mysteries, and
* How to decide which testing company best suits your needs.

What DNA tests are available for genealogy?

Three types of DNA test are available for anyone interested in exploring their family history:
1. y-chromosome DNA (y-DNA)
2. Mitochondrial DNA (mtDNA)
3. Autosomal DNA

To decide which is best for your purposes, here’s a brief explanation of what each test does, the results it provides and how it might help with your research.

What does each test do?

1. y-DNA

The y-DNA test traces the direct paternal line.

The y-chromosome remains virtually unchanged down the generations and is passed from father to son. Since surnames tend to follow the same route, the y-DNA test has become a popular and practical tool for researching individuals with the same surname. However, because only males carry the y-chromosome, only males can take this test. A woman would need her closest male relative to take the test, preferably her father, brother, paternal grandfather or paternal uncle.

What will y-DNA results tell me?

Well, that depends. The best that can happen is that the person tested matches one or more individuals with the same y-DNA profile. This means that the matched individuals have a shared connection (or ancestor) somewhere on the direct male line. However, the test alone does not tell you where the connection occurs. For that, you have to rely on genealogical ‘paper trails’, which is where this can get really interesting.

Let’s suppose, for example, that David Jones and Simon Jones (who have never met) discover they share a y-DNA match. David can trace his male ancestry back to the 1840s, but Simon has traced his family tree several generations further back. By comparing their family trees, David and Simon gain more information and try to determine the identity of their common male ancestor. Thanks to the y-DNA test, they can narrow the search to their direct male lines.

A lot of surname projects are using such evidence to build databases of common ancestry and relationships, which makes y-DNA testing so exciting right now. Some surname projects will even cover the cost of taking the test providing you agree to upload your results to their database. (You can find a partial list here, visit the Guild of One-Name Studies, or Google your surname of interest and DNA to see what comes up.)

The worst case scenario is that you find no matches. The most common reasons for this are that no living direct male connection exists, or no potential matches have tested (yet).

Who supplies home y-DNA tests?

At present, separate y-DNA tests are only available from FamilyTreeDNA.

Prices depend on the level of test. There are three levels (37, 67 and 111), based on the number of markers (locations) tested on the y-chromosome. More locations mean greater accuracy, but may not represent the best value for a limited budget. Ideally, 67 markers makes a good starting point, but many surname studies suggest 37, so you could easily begin with 37 markers and upgrade at any time without needing to take the test again.

2. mtDNA

Mitochondrial DNA has been used to test the direct maternal line, from mother to grandmother and so on. Unlike the y-DNA test, anyone can take it. The results are very similar to the y-DNA test, in that the person tested normally receives a list of mtDNA matches with people on the testing company’s mtDNA database. The idea is that your matches may know more than you about your shared relatives, much like in the Jones’ example above, only this time for your direct maternal line.

However, a recently published medical study of patients with symptoms of mitochondrial disease, has challenged the scientific assumption that mtDNA is only passed down to us through the female line, i.e. through our mothers and grandmothers. The study revealed that in some cases, mtDNA has been received from both the mother’s and the father’s side. This has raised some difficult questions for the use of mtDNA in tracing our direct maternal ancestors, since we can no longer assume that all matches must be connected by way of the direct mother line.

However, for anyone who has taken or intends to take an mtDNA test, it is not all doom and gloom. Your mtDNA is still your mtDNA and any matches found will still share it, it’s just that there may be a better strategy for establishing those connections than the one we currently rely on. Do ‘watch this space’ as there will be a lot of people looking for more clarity about this.

Who supplies home mtDNA tests?

FamilyTreeDNA is the only company to offer a separate mtDNA test.

3. Autosomal DNA

Humans have 22 pairs of autosomal chromosomes in addition to the pair of sex chromosomes (the x-chromosome and y-chromosome). Autosomes vary in size, the largest having some 2800 genes and the smallest around 750.

Autosomal DNA testing works on the basis that we inherit half our DNA from our mother and half from our father, who in turn inherited half of their DNA from each of their parents, and so on. Each of us is a mix of DNA from our direct ancestors. The further back you go, the less DNA you will have inherited from each of your direct ancestors. For that reason, the test is really only helpful up to about five generations back. (To trace your ancestral line beyond five generations, you would need the y-DNA or mtDNA.)

What will autosomal DNA results tell me?

This is where things get a little bit tricky. Autosomal DNA tests normally provide you with two different forms of results: ‘cousin matches’ and a map showing ethnicity percentages.

Let’s start with ‘cousin matching’.

Cousin matches are people within each company’s autosomal DNA database with whom you share parts of your DNA. Those shared elements will be from a common direct ancestor. But, who is it?
Unless known members of the same family are taking the test, you will have to compare family trees with those of your ‘cousin matches’ to figure out the source of the connection and precisely how you are related to each other. (Unlike the y-DNA test, your autosomal DNA will not help you narrow the search to just your direct male ancestors.)


All the autosomal DNA testing companies provide a map showing your DNA’s estimated ethnicity percentages. Each company has its own method of calculating these and defining geographical regions, so it’s quite likely these estimates will vary depending on your chosen company.

Autosomal DNA test suppliers

AncestryDNA, FamilyTreeDNA, MyHeritage, and 23andMe, supply autosomal DNA testing and provide ‘cousin’ matching. LivingDNA, which has partnered with FindMyPast, plans to provide this in the next few months. To access these matches, you will most likely need a paid subscription to the appropriate company’s online genealogy database. If you test with AncestryDNA, for example, you will need a paid subscription to the Ancestry website if you wish to make contact with your matches or view their family trees.

So, which supplier should I choose?

Each autosomal DNA testing company offers something slightly different, so it very much depends on which test(s) you wish to take, your budget, and other considerations, such as the size of each company’s database and geographical coverage.

Here are some tips to bear in mind:

1. AncestryDNA currently has the largest database. Ancestry doesn’t accept autosomal test results from any other company, but if you test with Ancestry you can transfer your data to FamilyTreeDNA and MyHeritage at no extra cost, so you can effectively access matches in three databases for the price of one. However, there are additional fees to access some of the newer, optional features, including chromosome browsers and ethnicity estimates. 23andMe also accepts some data, but it will depend on which version of microchip was used.

2. LivingDNA offers a 3-in-1 test. If you do not want relative matching (for now), providing the test taker is male and is sure they want a y-DNA, mtDNA and autosomal test, this option currently represents better value than purchasing each test separately.

3. LivingDNA is the only company to offer an ethnicity map broken down by British and Irish subregions. If you think you have British or Irish ancestors, this is certainly an option worth considering.

4. Remember, you can take more than one test. So, whatever you decide, you can still take further tests later.

Which will you choose?

Happy testing and good luck!

Further Reading

Tina Hesman Saey, ‘What I actually learned about my family after trying 5 DNA ancestry tests’, 13 June 2018.