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Best best dna test y-dna vs. mtDNA vs. autosomal DNA

What’s The Difference? Y-DNA vs. mtDNA vs. Autosomal DNA Explained (+ Tips for Choosing the Right One)

One of the most important things to check when looking for a good DNA ancestry testing service is the type of DNA they actually test.  It makes a huge difference in the type and accuracy of information you can learn from the test.

There are 3 basic types of DNA tested by ancestry DNA tests today:

  1. paternal DNA (Y-DNA)
  2. maternal DNA (mtDNA) and,
  3. autosomal DNA (atDNA)

The right DNA test for you depends on the kind of information you want to glean from your test.

Let’s look at each type of test in a more detail – and the information you will get.

Y-DNA:  paternal lineage

Map showing movement of Y-chromosome bearing humans

Map showing proposed pre-historic migration paths of the first humans who bore the Y-Chromosome. By Maulucioni, CC BY 3.0

This is the test you go for if you want to research your father’s side of the family. Since only males have the Y-chromosome which is passed on almost unchanged from father to son, you can trace a direct line between male members on your paternal side.

The Y-DNA test can only be taken by males. Women who want to trace their paternal side have to ask their brother, father, paternal uncle, paternal grandfather or paternal cousin to take the test for them.

With a Y-DNA test, it’s possible to go thousands of years back through your ancestry timeline. However it’s much more challenging to pin the exact genealogical period of a certain ancestor. You can only estimate how many many generations back they lived.

What Y-DNA tests do is compare STR Markers (short tandem repeat) for two different males.

The difference between their markers is used to determine how close they are in terms of relationship and generation.

If for instance you get tested for 37 markers and have a 37/37 match with someone else, there is a 50% chance you share a common ancestor within 2-3 generations. The probability that the ancestor is closer than 7 generations is 95%.

Most DNA testing companies test between 12 and 111 markers. Experts generally agree that 67 markers are enough to make a fairly confident prediction about the relationship between two people.

The more the number of markers tested the more refined the results will be. The price goes up too for tests with more markers. Family Tree DNA allows you to test for as few as 37 markers and as many as 500. Most other services only go as high as 67.

Comparing Y-DNA Results

Y-DNA results are only useful when compared to other people’s results. That’s how you can find out if you are related to another male. One of the things you can do to find relatives is join a surname project.

In most cultures, surnames are usually taken from the paternal side. This makes it easy to trace your father’s side of the family.

Family Tree DNA currently has over 9,000 surname projects. To get started, just search your surname on their homepage. Others to checkout include Cyndi’s List and ISOGG’s (International Society Of Genetic Geneology) own list of surname projects.

Most DNA testing companies also allow you to create a family tree use it to find other people with a shared ancestor.

mtDNA:  maternal lineage


mitochondrial DNA

Mitochondria are small internal cellular structures that serve as the body’s energy factories, and they have their own DNA called mitochondrial DNA or mtDNA.

Only mothers can pass mtDNA to her children.  mtDNA in sperm is destroyed either in the male genital tract or by the fertilized egg. As a result, only female mtDNA survives inheritance.

This means that by testing mtDNA in one female and comparing it to that of another female, one can determine how they are related, which is why mtDNA is used to trace your mother’s side of the family.

Because a mother passes mtDNA to both male and female children, both men and women can get value from this test.

By comparing your mtDNA to that of other people, you have a chance of finding a relative from your maternal side.

As with Y-DNA, mtDNA has several limitations. The biggest one is the limited set of ancestors it can trace. You can only trace someone with a direct maternal line to your mother. So it’ll go from your mother to your mom’s mom to her mom’s mom and so on.

mtDNA ignores many ancestors on the paternal side of your mother’s lineage, as well. This can seriously limit your ancestry search and sometimes lead to unexpected results.

For example, one African American woman’s mtDNA test results did not show any African ancestry, only European. This is possibly because a single woman in her maternal lineage was of European decent. That single individual threw her whole ancestry search off-track by ignoring her other black ancestors.

Interesting fact: If former President Obama took an mtDNA test, it wouldn’t show any African ancestry. That’s because his mother has a mostly English ancestry.

Autosomal DNA (atDNA): long-term ancestry and recent lineage

An autosome refers to the remaining 22 numbered chromosomes except for your 23rd, sex chromosome (X-Y).

Unlike Y-DNA and mtDNA, autosomal DNA is inherited from both parents. So you can use it to trace either side of your family.

Everyone can get value from an autosomal DNA test.

The major DNA testing providers rely mostly on autosomal DNA testing.

But the timescale is limited with this test – you can use this test to find relatives up to the second cousin level. Beyond that, you’ll need to use a family tree or other types of DNA testing to identify additional relatives and shared ancestors.

Most DNA test providers provide family finder tools you can use to dig up more information that can help you fill the gaps.

Autosomal DNA testing also tells you a lot about your long-term DNA ancestry (haplogroup) composition as well as the location and migration patterns of your ancestors.

But it cannot tell you which side of your family those long-term ancestors came from. For that, you’ll have to get other family members tested, create a family tree and use additional details such as surnames.

Which Test Should You Buy?

Get a Y-DNA test when you want to trace your father’s lineage or to confirm paternity. Only males can take this test, because the Y-chromosome only exists in males.

Get an mtDNA test when you want to trace your mother’s lineage. Both males and females can take this test, because the X-chromosome is present in both sexes.

Get an autosomal DNA test if your focus is to identify unknown living or recently-deceased relatives (within 2 generations), to understand your long-term ancestry and tribal migrations, or to help you build a family tree.

The three leading autosomal ancestry DNA tests include Family Finder, AncestryDNA and 23AndMe.

Read my in-depth comparison of all three or use the chart below to see which one is right for you.

Best DNA Test
AncestryDNA package
Family Tree DNA
FTDNA icon
Best Choice IfYou want quick and easy-to-read ancestry reports. Also offers health screening.You want to find as many family members as possible, to build your family tree.You want in-depth information about your DNA ancestry. Professionals choose this one for a reason.
Learn More
Learn More
Learn More
SalivaSalivaCheek Swab
Custom Illumina HumanOmniExpress-24 format chipIllumina
10 Million15 Million3 Million
Raw Data
Raw Data
In Research
Yes (with your consent)Yes (with your consent)Yes (with your consent)
6-8 weeks6-8 weeks4-6 weeks
Visit Website
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About the Author Charles McKnight

I'm just another amateur genealogist investigating my American-Scots-Irish lineage. I built MyFamilyDNATest.com after buying all of the leading DNA tests to discover everything I could about my family history. Hopefully, this site will save you time and demystify the emerging science of DNA-based genealogy, for your family project.

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