What's the Difference Between Autosomal, Mitochondrial, and Y-Chromosome DNA Testing?

Before you begin DNA testing for family history purposes, it’s important to understand the 3 different types of DNA testing and what the benefits are of each.

What are the 3 Main Types of DNA Testing?

1. Autosomal

The 3 main types of DNA testing are autosomal, mitochondrial, and Y-chromosome testing. Autosomal testing – also termed atDNA testing – looks at 22 of the 23 pairs of chromosomes that make up our DNA. The 23rd pair of chromosomes is the pair that determines your sex – XX if you are female and XY if you are male. The 22 chromosomal pairs that are the same for men and women are called autosomes, hence autosomal testing, and they carry genetic information from both sides of your family tree.

2. Mitochondrial (mtDNA)

In contrast to autosomal (atDNA) testing, mitochondrial (mtDNA) and Y-chromosome (Y-DNA) testing look at only the 23rd pair of chromosomes. Mitochondrial testing examines the mitochondria, which are microscopic strands inside every cell. Your mitochondria are inherited from your mother and can be passed on to both males and females, but only female mitochondria are preserved and passed to the next generation. This means that both men and women can take an mtDNA test, but you’ll only get information about your maternal line.

3. Y-Chromosomal (Y-DNA)

Y-DNA testing is only a viable option for men since it looks at genetic markers on the Y-chromosome, which is only found in men. It’s similar to the mtDNA test because it will only tell you about one line in your family – in this case, the paternal line. Although women can’t take the Y-chromosome test, they can get a male relative to take the test to uncover more information about paternal history.

Which Type of DNA Testing is the Most Accurate?

Both mtDNA testing and Y-DNA testing are more accurate than autosomal tests if you want to learn about distant ancestors. Because autosomal tests reveal such a variety of genetic activity from every branch of your family tree, they are less accurate across multiple generations. Although anyone with whom you share genetic material is related to you somehow, atDNA tests aren’t recommended beyond six generations at the most.

In contrast, mitochondrial tests and Y-chromosome tests can be extremely accurate across dozens of generations. It’s like the difference between shining a narrow beam of light instead of allowing that same light to shine across a wider area. A narrow beam of light will stretch further into the distance, but a wider beam will light up more ground around you.

Scientists have traced mitochondrial DNA all the way back to a woman referred to as ‘mitochondrial Eve,’ who is believed to have lived around 200,000 years ago, which shows the accuracy of mtDNA tests. ‘Eve’ is the most recent common female ancestor for everyone alive today.

That means that every human being on the planet shares the DNA of this single woman, not that she was the first human woman, ever. She was just the most recent woman whose female line continued unbroken until today.

Similarly, scientists were able to use Y-DNA tests to identify ‘chromosomal Adam’ as the most recent common male ancestor of all humanity (but again, not the first human man). Scientists have placed him as having lived around 100,000 years ago, which isn’t at the same time as mitochondrial Eve, but they do have theories to explain that, including the frequency of polygamy.

What is the Best Type of DNA Testing?

The best type of DNA testing is going to depend on what you want to achieve. If you’re searching for more relatives, autosomal testing will help you find more relatives than Y-DNA or mtDNA tests. On the other hand, if you’ve hit a brick wall in tracing your ancestors beyond a few generations, Y-DNA or mtDNA testing could help you move past it, or work out which of a few possible ancestors with similar names is the one from whom you’re descended.

The Best DNA Testing Kits

There are many DNA testing kits out there. Here are some of the best for the 3 different types of DNA testing.

MyHeritage

MyHeritage is more than just a DNA testing site – it’s a huge online archive of valuable genealogy documents and guidance about learning more about your family history. MyHeritage’s useful genealogy tools help you make the most of your DNA test results and other resources guide you in your search to understand more about your ancestors. MyHeritage also hosts a DNA database of over 1 million people and the largest international network of family trees.

• Only offers autosomal testing
• Helps you combine your results with family history data
• SmartMatches feature to help you find more relatives
• Useful genealogy tools enable you to make the most of your results

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LivingDNA

LivingDNA offers extremely in-depth DNA tests for anyone who wants to know more about their family history beyond a few generations. It uses very specific and advanced DNA tests in order to give more precise information about your region of origin, dividing the world into 80 regions, and the British Isles into 21 regions, more than any other DNA testing site. LivingDNA also offers a unique interactive map and geographic mapping to show you exactly where in the world your family originates. The cheek swab DNA test is easy to use, and although it's more expensive than some other options, the results you'll get are very detailed and can easily be shared with other DNA databases to help you access more matches.

• Offers all 3 types of DNA testing -- autosomal, Y-DNA, and mitochondrial testing
• Tests are more expensive than some other options
• Has the most detailed resources for anyone with family from the British Isles
• Cheek swab tests are easy to use

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23andMe

23andMe is unusual in offering both ancestry and health-focused DNA testing. This means that you can learn about any lurking genetic diseases as well as the likelihood that you'll develop lactose intolerance and your natural athleticism. 23andMe's ancestry tests are both autosomal and mitochondrial so that you can discover more relatives as well as tracing your family history back through many generations.

• Fast turnaround time, with results returned in 6-8 weeks
• Both autosomal and mitochondrial DNA testing, but no Y-chromosomal tests
• Extensive genetic health report option
• Only a few genealogy tools available

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Ancestry

AncestryDNA offers extensive family history tools and genealogical archives alongside useful DNA testing. Its popularity means that it's one of the best choices for finding long-lost relatives since you have better chances of finding a family member on the database. The tests are easy to use and have a very good reputation for reliability. You'll be able to explore the impact of your test results using Ancestry’s online family history tools.

• Only offers autosomal testing
• Fast turnaround of 6-8 weeks
• Thousands of online family trees and millions of stored DNA profiles make it easier to find relatives
• Detailed ethnic makeup breakdown that divides the world into 150 regions

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Vitagene

Vitagene is focused on using your genetic information to provide you with better health and lifestyle advice, rather than on genealogy, but the reliable tests can help you learn more about your family history too. The turnaround time is among the fastest available and the easy-to-use cheek swab also speeds up the process. Vitagene sends you information about the geographic origins of your DNA as well as a detailed health and vitality report.

• Only offers autosomal testing
• Extensive health and vitality report that uses your genetic information to give lifestyle advice
• Very fast turnaround of 4-6 weeks

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Which Kit Is Best for You?

Now that you understand the difference in the science behind DNA testing kits, which will you choose? If you’re looking to find distant relatives that are alive nowadays, atDNA tests may be the right choice for you. If, however, you’re looking to trace your family back many generations, mtDNA or Y-DNA might be your best bet.