For the last few years, DNA tests have skyrocketed in popularity. When combined with genealogy, these tests can prove an invaluable resource to prove relationships, find new relatives and break through brick walls. However, the advantages are not always clear for newcomers. 

In this guide, you will learn about DNA, the types of tests you can take, and how they might help you in your family history. I’ll also share links to the main DNA kits providers and compare their services so you can pick the best one for you.

What is DNA and Why it is Important

DNA (or deoxyribonucleic acid) is the molecule that encodes the genetic instructions for building and operating all living things. DNA defines each person’s biological characteristics, which are essentially determined by proteins. These proteins are encoded in genes or specific sequences of DNA nucleotides.

The order of the nucleotides determines the order and types of amino acids that must be put together to make a protein. There are only four DNA bases (A, T, C and G), but their combination can create 20 amino acids. For example, tryptophan is an amino acid needed for normal growth in infants and for nitrogen balance in adults, and it’s encoded by the letters (bases) UGG. 

Strings of nucleotides are bonded to form helical backbones and assembled into chains of base-pairs. This is the drawing of DNA that you’ve probably seen. The colored rods are the bases that combine (C always with G, A always with T) to create the proteins that make us:

DNA Nucleotid Bases

The human genome contains around 20,000 genes (or stretches of DNA that encode proteins), however, they only account for about 1.2 percent of the total genome. The other 98.8 percent is known as noncoding DNA.

Regardless of the DNA being coding or not, their strings are coiled into packages called chromosomes, which are found in the nucleus of our cells. Each nucleus has 23 paired chromosomes – one air being sexual chromosomes, either XX for women or XY for men. Cells also have mitochondria outside the nucleus, and we will see in this article how this mitochondrial DNA, inherited only from our mothers, can be of extreme importance in genealogy. 

The DNA you inherit from your ancestors is unique to you. You receive 50% from your mother and 50% from your father (which segments from each are randomized), who in turn had received 50% from each of their parents, and so on.

That’s why, when you can look at your DNA, you’re looking at that of all the people that came before you. Something that can definitely help us in genealogy. 

Different Types of DNA Tests

There are three main types of DNA tests you can take, the main ones being: Autosomal, Mithocondrial, and Y-Chromosome, depending on what you are trying to uncover or learn more about.

Some tests involve spitting into a tube, while others are done by swabbing the inside of the cheek with a small brush. The two techniques offer the same kind of results, although the second is easier to post. It’s worth noting also that DNA tests for genealogical purposes never involve needles, blood or urine; only police tests do.

Although genetic testing has made tremendous strides in the past few years, it’s still a new field so the results might not exactly be what you were expecting. That’s why it’s important to know what they are, and what advantages they can offer to compliment your genealogical research.

The most popular DNA test providers are Ancestry, MyHeritage, and FamilyTreeDNA (this last one being the only one that offers mitochondrial and Y-Chromosome tests). 

Ancestry DNA Kit
A DNA test from Ancestry, showing the kit which includes box, instruction manual and accessories for the sample.

Autosomal Tests

Autosomal DNA (or atDNA) is inherited from our ancestors across the whole family tree. It includes all the chromosomes and can give great results for the last 5–7 generations.

This type of test is the most commonly promoted through ancestry testing companies. It receives different names depending on the provider, such as “Family Finder” or “Ancestry DNA”, and the cost is usually between £45 and £70

Because you only inherit half of each of your parents’ DNA, some of your ancestors “fall off” your genetic tree. Autosomal DNA can prove extremely valuable for finding or verifying family, especially if you match with people who are either very close genetically (such as a parent, sibling or first cousin) or that have worked on their family trees and can compare it to yours. 

Mithocondrial Tests

Mitochondrial DNA, or MtDNA, is found in a cell’s mitochondria. These are passed from a woman to all her children, regardless of whether they are male or female, and therefore are used to trace the female line. 

Human mitochondrial DNA was the first significant part of the human genome to be sequenced because it only has 16,569 base pairs. This means that, unlike other tests, once you get this one done you’ll never have to do it again. 

Not all DNA testing companies offer tests for mitochondrial DNA. We recommend FamilyTreeDNA, because it has the largest database of people tested so it gives you more chances of finding relatives. The cost of this test is around £120 to £180.

Y-Chromosome Tests

The Y-Chromosome is one of the two paired sex chromosomes, and it’s only carried by men. This means that it’s passed from father to son. If you’re a female, you can still test a father, brother or paternal male first cousin that bears the surname of your father. 

When you compare the Y chromosome of two males, you can determine whether they share a common patrilineal ancestor and possibly predict a man’s likely surname. Male ancestors carried their Y-DNA line along their migrations too, which allows you to trace your paternal ancestry across different countries.

Y-DNA tests are available in different marker quantities. The minimum is 12 markers, and the biggest 700 short tandem repeats and 100K SNPs. If you are looking to begin Y-DNA testing, the Y-37 Marker test allows you to become familiar with Y-DNA results.

The cost is higher than autosomal and mitochondrial tests, between £70 to £400 depending on the number of markers you want to analyze. Luckily, companies like FamilyTreeDNA allow you to start with a smaller test and increase the markers when you wish to do so. 

An example of a Y-DNA analysis, showing the haplogroup and results for different markers.
An example of a Y-DNA analysis, showing the haplogroup and results for different markers. Image courtesy of FamilyTreeDNA.

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