Types of DNA Tests used for Genealogy

DNA testing has revolutionized genealogy, allowing individuals to uncover their ancestral origins, connect with distant relatives, and validate (or dismiss) family relationships. There are three primary types of DNA tests used in genealogy:

• Autosomal DNA (abbreviated as atDNA),
• Y-DNA – Focuses on the male (paternal) line
• Mitochondrial DNA (abbreviated as mtDNA).

Each serves a different purpose, detailed below, and provides unique insights into an individual’s heritage, as well as to uncover new family members, distant and close.

Autosomal DNA (atDNA) 

Autosomal DNA testing is the most commonly used genetic test for genealogy. It analyzes DNA inherited from both parents and provides information about recent ancestry, typically within the past 4 – 6 generations. This test examines the 22 pairs of autosomes (non-sex chromosomes) and can identify relatives on both the maternal and paternal sides of the family.

atDNA was first offered to the public as far back as 2000 by FamilyTree DNA, however that early testing involved a blood sample. The first saliva-based testing was made available by 23andMe in 2007, but it was only when AncestryDNA was launched by Ancestry.com that it became a known and common practice – mainly because of the advertising budget of Ancestry.

All popular genealogy services offer autosomal DNA testing. The results typically include ethnicity estimates, which indicate the most common geographic regions of a person’s ancestry, and a list of genetic matches—individuals who share DNA segments and are likely related. However, autosomal DNA inheritance follows a random pattern, meaning that distant ancestors’ DNA may not always be detected.

Your results may also contain “personality traits” and health-related estimates, but these should be reviewed cautiously and only considered as a “fun” add-on.

Y-DNA Testing

Y-DNA testing focuses on the Y chromosome, which is passed down exclusively from father to son. This makes it an effective tool for tracing direct paternal lineage. Unlike autosomal DNA, which recombines every generation, Y-DNA remains relatively unchanged over many generations, preserving a clear paternal ancestry line that can go back thousands of years!

Doing a Y-DNA test can help confirm surnames and establish connections between individuals who share a common male ancestor. This test is particularly useful for surname studies and investigating deep paternal ancestry. Only males can take a Y-DNA test, but women can explore their paternal lineage by having a close male relative (such as a father, brother, or uncle) take the test on their behalf.

Mitochondrial DNA (mtDNA) 

Mitochondrial DNA testing traces the maternal line by analyzing the DNA found in mitochondria, which are inherited exclusively from the mother. Unlike nuclear DNA, mtDNA does not undergo recombination, making it a powerful tool for studying deep maternal ancestry going back hundreds of generations.

Both men and women can take an mtDNA test since everyone inherits mitochondrial DNA from their mother. However, mtDNA changes very slowly over generations, so while it provides valuable insights into ancient maternal origins, it may not be as useful for finding recent relatives.

My Own Experience

I did my first atDNA test through AncestryDNA back in 2014. I have since uploaded that raw data extract to FamilyTreeDNA, GEDMatch and MyHeritage and made new discoveries through each of those platforms. I was also fortunate that my mother also did her atDNA test when she turned 90. Being able to compare and combine the results of both tests has been a huge benefit. I always recommend that the oldest living relative in your family should do a DNA test. Once they are gone, the information hidden in their DNA goes with them.

Hint: You really only need to test once, and then use the raw data to explore other databases.

I have also done a Y-DNA through FamilyTreeDNA (Y-111) to try and go back further on my paternal side of the tree. I’m still working through the myriads of new contacts, surnames and other information it surfaced. I’ll write more on this topic at a later date.

The Bottom Line

Each type of DNA test offers unique benefits for genealogical research. Autosomal DNA is best for discovering recent ancestors and connecting with living relatives. Y-DNA helps trace paternal lineage, while mtDNA provides insights into maternal ancestry. By understanding these different types of DNA testing, this will hopefully help you choose the most suitable test to unlock the secrets of Your Family History.