GENOMIC GENEALOGY

DNA Testing

While it requires some complicated science, the process of DNA testing is relatively simple to understand. But before we get to that it's important to understand what is being tested. As previously discussed, the human genome consists of 23 pairs of chromosomes. 22 pairs of autosomal chromosomes and one pair of sex chromosomes (Bolohan, Ciorpac, Mățău, & Gorgan, 2016). These 23 pairs of chromosomes comprise approximately 3.2 billion base pairs and these base pairs encode approximately 20,000 genes The small mitochondrial genome consists of only 37 genes (Toledo & Saltsman, 2012).

On the DNA page we discussed the fact that all humans are 99.9% genetically identical (National Human Genome Research Institute, 2018). Given this fact, there is often little point testing your entire genome. While full genome sequencing is available it is time-consuming and therefore costly. For the purposes of ancestral DNA testing, we are interested in two things. Firstly, we are interested in the DNA that you posses that is known to vary between humans based on geographic origin. This will give us an idea of your ethnic ancestry. And secondly, we are interested in the DNA that is known to vary between humans that you share with other people. Sharing DNA that is known to vary between humans with other people is a good indication that you are related to them.

So instead of looking at 3.2 billion bases pairs, most ancestral DNA tests look at SNPs. An SNP, or single nucleotide polymorphism, is a single base pair that is known to vary between humans. Individual SNPs correlate to specific geographic regions or populations. If you share multiple SNPs in a row with another person, it is assumed that the DNA between the individual SNPs is the same. The more SNPs you share with someone in a row the more closely related you likely are to them. Humans have around 11.5 million SNPs (Madsen, Villesen, & Wiuf, 2007). Most ancestral DNA testing only looks around between 700,000 and 800,000 SNPs. This is done in order to keep the cost of tests down and because you don't actually need to look at every SNP. Looking at a range of SNPs that are distributed across the genome is sufficient to gain a reasonable approximation of a person's ethnic ancestry and to match them to people to whom they are related.

Health Testing

Some ancestral DNA testing companies also provide health testing for an additional fee. This testing is different as it is looking for specific variants (alleles) of genes that are related to health and disease. Should you choose to undergo this kind of testing it is important to understand what this testing is actually telling you. A specific variant of a gene might be correlated with a specific health condition or disease. But simply having that variant of that particular gene doesn't mean you are guaranteed to develop that health condition or disease. If you undergo this type of testing and receive a result that indicates you have a variant of a gene associated with a particular health condition or disease it is important that you discuss this with your doctor. They should be able to tell you whether it is something you should be concerned about and whether any action needs to be taken.

How Do DNA Tests Work?

For the remainder of this discussion, we will focus on ancestral DNA testing only. So, how does a test work? Most tests involve the collection of a saliva sample. Some will involve the collection of a buccal swap which involves rubbing a swab on the inside of your cheek. The kit you receive will explain how to collect the sample and how to package it for shipment back to the testing company. When the testing company receives the sample they extract your cells from it and then break them open in a process called cell lysis in order to free the DNA inside. The DNA is then washed and purified before being copied so that there is sufficient DNA to test for each SNP. The DNA is then denatured. Denaturation is the process of splitting the strands of DNA down the middle to separate the two sides. The DNA is then cut up into smaller pieces and dyed with a fluorescent dye. The dyed pieces of DNA are then applied to a microarray chip. The chip has a well for each SNP that has complimentary DNA affixed to it. If a person has the SNP is question their DNA will bond to the affixed DNA in the well. The SNPs can then be read using a scanner which looks for the presence of the fluorescent dye in each well (National Human Genome Research Institute, 2020). This is a simplification of the process but if gives you an overall idea of how tests are conducted (see Figure 8: DNA Testing Process).

DNA Testing Providers

Different ancestral DNA testing companies will look at a slightly different number of SNPs depending upon the microarray chip they are using. There are many providers of ancestral DNA testing in the market. When choosing a provider, it is important to consider the full scope of their service. Not only are you having your DNA tested but you are also being matched against a database of other users to see who you are related to. The larger this database the more relatives you are likely to uncover. Let's look at some of the tests that are available.

AncestryDNA

AncestryDNA is an American company that has the largest database of DNA tests of any DNA testing provider. This means that you're more likely to find more relatives if you test through them. Ancestry.com also has the largest repository of publicly available original historical records making it a great place to conduct genealogical research. Many people find it convenient to have their DNA test results in the same place that they perform their genealogical research. If you're using Ancestry.com for your genealogical research it's worth considering having your DNA test done through AncestryDNA.

AncestryDNA only conducts autosomal DNA testing, meaning if you want mtDNA or Y-DNA testing you will have to use a different testing provider.

The cost for an AncestryDNA test is AU$129 (US$99 or £79), however they often offer discounted prices on their tests, particularly around holidays. AncestryDNA also offers a combined ancestry and trait test for AU$159 (US$119 or £94).

Unlike some other providers AncestryDNA will continue to provide you with updated reports whether you have an on-going membership with them or not. However, if you wish to use Ancestry.com for genealogical research, you can often obtain a discount on a membership if you purchase an AncestryDNA test. Ancestry.com memberships start at AU$21.99 (US$24.99 or £10.99) per month.

Ancestry operates numerous national websites and the memberships differ from site to site in terms of cost and which record collections are included. It can be more cost effective to take out a membership on the national site where your ancestors were from rather than the national site for the country you are located in. For example, if you live in Australia but your parents or grandparents were from the UK it might be cheaper to take out a membership on the UK site to obtain access to the record collections you require.

Access AncestryDNA's site here.

23andMe

23andMe is an American company and is the second largest provider of DNA testing. They offer autosomal DNA testing for US$99 (£79). For people in the United States or the United Kingdom they also offer a combined ancestry and health test for US$199 (£149). 23andMe offers an on-going membership at a cost of US$69 (£59) per year that provides access to pharmacogenetics reports (reports on how you may react to certain medications) and access to new reports as they become available. 23andMe is currently the only DNA test provider that includes an estimate of a person's Neanderthal DNA.

Access 23andMe's site here.

FamilyTreeDNA

FamilyTreeDNA is an American company that unlike many of the other DNA testing providers offers autosomal, mtDNA, and Y-DNA testing. Autosomal testing costs US$79. mtDNA testing costs US$159. And Y-DNA testing ranges from US$119 to US$449 depending upon the amount of the Y-chromosome that is tested. Remember that only people with a Y-chromosome can take a Y-DNA test but those without a Y-chromosome can have a male relative take the test for them (the male relative must be from the same paternal line). No on-going membership is required.

Access FamilyTreeDNA's site here.

LivingDNA

LivingDNA is a UK company that offers autosomal testing starting at AU$169 (US$99 or £99). Their test covers the entire world however they offer a deeper level of information about African, British, and European ancestry so if your ancestors are likely to have come from one of these three geographic locations this might be a test to consider. They also offer a combine ancestry and wellness test that looks at fitness and nutritional response for AU$259 (US$179 or £179). No on-going membership is required.

Access LivingDNA's site here.

MyHeritageDNA

MyHeritageDNA is an Israeli company that offers autosomal DNA testing. Ancestry.com's DNA might be the most popular test in the world, but MyHeritageDNA is the most popular DNA in Europe with the third largest DNA database. MyHeritageDNA tests cost AU$149 (US$89 or £79). MytHertiageDNA also offers an on-going membership to the MyHertiage platform that provides access to genealogical records starting at AU$109 (US$89 or £59) per year.

Access MyHeritageDNA's site here.

tellmeGen

tellmeGen is a Spanish company that offers autosomal testing starting at AU$159 (US$89 or £75). Their Starter DNA Kit includes ancestry, traits and wellness and their Advanced DNA Kit includes additional heath information. The Advanced DNA Kit starts at AU$239 (US$149 or £139). They offer single kits, children's kits with child-size swabs, and family kits.

Access tellmeGen's site here.

Adntro

Adntro is a another Spanish company that offers autosomal testing starting at €89. Their Entry kit includes ancestry and nutrition informastion. Their Basic kit (€99) includes ancestry, nutrition, and fittness informstion. And their Premium kit (€149) includes behavioural, pharmacogentic, and disease information, traits and wellness and their Advanced DNA Kit includes additional heath information.

Access Adntro's site here.

Nebula Genomics

Nebula Genomics is an American company that is different from the other ancestral DNA testing providers discussed here. Rather than looking at individual SNPs, Nebula Genomics offers partial and full genome sequencing. This means that rather than looking at individual SNPs they look at every nucleotide (or every nucleotide in specific regions of the genome if undergoing partial genome sequencing). Partial genome sequencing costs US$499. Full genome sequencing starts at US$924. These prices include a lifetime Plus Nebula Explore™ Membership. This membership provides on-going updates to your results. Nebula Genomics ships tests to 187 countries around the world including Australia, New Zealand, Canada, and the United Kingdom.

Access Nebula Genomics' site here.

About Prices

All prices are accurate as of 4th June 2023. Prices are subject to change and you should consult with the relevant ancestral DNA testing provider to confirm their current prices. Testing providers often run promotions that offer discounted tests. These discounts can often be significant. Prices do not include the cost of shipping.

Genetic Matching Services

When you test through a particular DNA testing provider you will be matched with other people in their database to whom you are related. This is great but it does mean that you are limited to people in that DNA testing provider's database. For example, if you test with AncestryDNA you will only be matched with people who also testing with AncestryDNA.

However, there are ways you can be matched with relatives who have testing through a different DNA testing provider. Some DNA testing providers allow you to upload your raw testing data from other DNA testing providers which they will then match to users in their database. For example, FamilyTreeDNA allows you to upload your testing data if you tested with AncestryDNA, 23andMe, or MyHeritageDNA free of charge. Similarly, Nebula Genomics allows you to load your testing data if you tested through AncestryDNA or 23andMe.

There are also websites that specifically exist for people to upload their testing results in order to be matched to people who tested through other DNA testing providers. GEDmatch is one such service. You can upload testing data from more than 20 DNA testing providers including AncestryDNA, 23andMe, LivingDNA, FamilyTreeDNA, MyHeritageDNA, or tellmeGen. The site can then match you to users in their database regardless of which DNA testing provider they tested through. The site also features some very useful tools to analyse ethnicity as well as the ability to compare your DNA data to archaic DNA samples from specific people who lived thousands of years ago, including Neanderthals.

Access GEDmatch's site here.

Genetic Test Analysers & Tools

In addition to genetic matching websites there are also websites that allow you to analyse the DNA results that you have received from a DNA testing provider. When you receive genetic test results it can be difficult to know how to interpret them or what to do with them. DNA Painter has tools that you can use to estimate the relationship between yourself and someone you have been matched to. This can help to focus your research on the most likely relationships rather than trying to cover every possibility. DNA Painter also has tools for chromosome mapping and for identifying unknown ancestors from groups of genetic matches.

Access DNA Painter's site here.

Ethnicity Estimates

When you receive your results most ancestral DNA testing providers will supply you with an estimate of your ethnicity. It is important to understand what these estimates are telling you and what they are not telling you. An estimate is just that: an estimate. They are not conclusive.

You might be of the understanding that you have ancestry from a particular part of the world or from a particular population. Let's say it's your understanding, based on stories that you have been told, that you have some Jewish ancestry. But you receive your results and they don't show any Jewish ancestry. Does that means you don't have any Jewish ancestry? No. Remember that all humans are 99.9% identical (National Human Genome Research Institute, 2018). It is therefore entirely possible that the DNA you inherited from your Jewish ancestors are contained in that 99.9%. Meaning that you have DNA from your Jewish ancestors but there is no way of telling that it is from them specifically because everyone shares it. It is of course also a possibility that you don't have any Jewish ancestry. Family stories are not always accurate. And this is where genealogical research comes in. Through research you should be able to prove or disprove the idea that you have some Jewish ancestry.

So are these tests just wrong? No, they're just not perfect. If a test tells you that you have German and Scottish ancestry you almost certainly do have German and Scottish ancestry. But you might also have Welsh ancestry that the test didn't pick up. Again, this is where genealogical research comes in to fill in the gaps. A test will likely give you a good broad understanding of the vast majority of your ancestry. But when it comes to the small trace amounts of ancestry from particular geographic locations or populations this is where these tests become less accurate.

Another important thing to understand is that there are two components to any test. The test itself and the interpretation of the test. The interpretation of any test is based upon the DNA testing provider's understanding of the relationship between specific SNPs and particular geographic locations or populations. This understanding is based upon research and this research is on-going. So you should expect over time that your ethnicity estimate will be updated by your DNA testing provider as more research is done.

Genetic Privacy

Before undertaking any DNA testing provider's test it is important that you read their privacy policies. You need to know how secure your genetic data is and what it might be used for. For example, some DNA testing providers and DNA test analysers cooperate with law enforcement in an attempt to solve serious crimes and to identify unknown human remains. Some DNA testing providers or DNA test analysers offer the option to opt out of this kind of participation and it's important that you understand what you are agreeing to.

In recent years law enforcement has used DNA databases to solve numerous high-profile cold cases, particularly in the United States. The most notable of these was the successful identification, arrest, and prosecution of California's Golden State Killer who was responsible for 12 murders in the late 1970's and early 1980's. In that case the GEDMatch database was used to identify a close relative of the suspect and then genealogical research was conducted to identify him (Kaiser, 2018). If you wish to upload your data to GEDMatch but do not wish to participate with law enforcement investigations GEDMatch offers the option to opt out of this kind of participation.

FamilyTreeDNA allows their database to be used by law enforcement to identify unknown human remains or in the case of an unsolved homicide, sexual assault, or abduction. However, they offer the option to users to opt out of having their genetic data used for these purposes.

AncestryDNA, 23andMe, LivingDNA, MyHertiageDNA, tellmeGen, and Nebula Genomics do not currently cooperate with law enforcement except where a court order is issued that requires them to do so.

DNA databases are a significant resource for scientific research and DNA testing providers will sometimes make their databases (or parts of their databases) available to researchers. Typically, you will be offered the choice of whether you wish your data to be used for scientific research or not when you sign up. It is strongly recommended that you always read a DNA testing provider or DNA test analyser's privacy policy before using their service.

To obtain more information about DNA testing including recommendations that take into account your specific circumstances please see the Consultation page for information and use the Contact page to request a consultation.