DNA Testing for Genealogy
Family history societies are abuzz with excitement as more and more members are using DNA testing as an additional family history research tool.
Due to technological advances and affordable prices, DNA testing is becoming very widely used by genealogists to confirm traditional research and connect with biological relatives.
CDFHS has a thriving DNA Interest Group, and we welcome anyone who would like to join us at any of our meetings – from complete beginners wanting to know where to start, to experienced testers willing to share their knowledge, success stories, or explore further options. We also run a regular Drop-In DNA Clinic offering individual assistance.
Introduction to DNA Testing for Genealogy
What is Genetic Genealogy?
Genetic Genealogy is the use of DNA testing in combination with traditional genealogy and traditional genealogical and historical records to infer relationships between individuals.” – Wikipedia
Goals & Benefits
You may want to:
- discover branches of your tree not found through regular research,
- confirm or disprove family relationships,
- find cousins with whom to share research & photos,
- determine if persons who share your surname are related,
- discover your ancient origins/ethnicity/admixture,
- solve long-standing research ‘brick walls’,
- identify biological family (adoptees, donor conceived, foundlings), or
- you may simply be curious to see what your DNA reveals.
Don’t let the scientific nature of DNA scare you off, as once the basic test types are understood, the minimum technical know-how is email in order to contact your DNA matches.
Collaborate with your new-found genetic relatives using your traditional genealogical skills to determine your ancestors-in-common.
The DNA Test Kit
DNA kits are ordered online from the US, they arrive in the mail, then after testing you post your kit back in the pre-addressed envelope or package.
The DNA tests themselves are very simple, consisting of either:
- cotton-ended swabs that you wipe inside your cheek, or
- a small tube in which you collect a saliva sample.
Once your DNA sample has finished processing, your results are added to a very large database and you are given an online account to manage them.
Even if you have no close matches initially, large numbers of people are testing each week, and you will continue to receive new matches regularly.
The most popular and fastest-growing test type for genealogy is called ‘Autosomal DNA’. Autosomal DNA is inherited from all ancestral lines, so anyone can be tested and matches can be descended from anyone on the chart below, up to about 6 generations back (and possibly further). A list of matches is provided in your online account, with the closest relatives at the top of the list.
Relationships are estimated based on the percentage of shared DNA, eg. 50% for a parent, child or sibling; 25% for a grandparent, aunt/uncle, half-sibling, niece/nephew; 12.5% for a great-grandparent, first cousin, great aunt/uncle; 6.25% another generation removed, etc.
Test your elderly relatives if possible, as their DNA matches can be much stronger than the next generation down. Testing known cousins (and confirming new cousins) is particularly useful, as it helps isolate the lines upon which you both share matches with other people.
Males inherit a y-chromosome from their father, through his father, his father, etc, on the direct paternal line, as per the blue boxes on the chart above. Y-DNA tests can determine if a male descends from the same male as another male who has tested. Y-DNA generally remains unchanged for many generations, but occasional mutations can help define particular branches. Y-DNA testers can join a surname project to compare origins of other men with the same surname. Males with unknown fathers (adoptees, donor-conceived, foundlings) can sometimes determine their biological father’s surname using Y-DNA. Females can test a male relative (eg. brother) to determine their paternal ancestry.
Everyone inherits mitochondrial DNA from their mother, through her mother, her mother, etc. on the direct maternal line, as per the pink boxes on the chart above. Males inherit mtDNA but do not pass it on to their children. As it can remain unchanged for generations, mtDNA tests can determine if someone descends from the same direct female as someone else who has tested. It can be useful in situations involving a question of maternity amongst mothers, daughters, maternal aunts etc. It can be used to check if two females (eg. with common surnames and from the same place) may have been sisters, eg. by testing a direct female descendant from each line (or a son of the most recent female).
Autosomal tests also include an estimate of your admixture/ethnic origins, ranging from around 200 to 2000 years ago.
Autosomal DNA results will also include some X-chromosome matches. The X-chromosome has specific inheritance patterns, different for males and females, so it can help isolate matches to particular lines of your ancestry.
DNA Testing Companies
There are three DNA testing companies for genealogical purposes: Family Tree DNA, 23andMe, and AncestryDNA. For the current prices and a comparison of each companies’ features, see Which DNA testing company should I use?
Family Tree DNA hosts over 9000 projects, including for surnames, geographical regions, and haplogroups.
Irish DNA, British Isles DNA by County, Australian Settlers, Australian Convicts, and New Zealand DNA are just a few projects that may be of interest.
The favourite amongst genealogists who don’t have a specific need to test the direct male or female lines is the autosomal DNA test. AtDNA will match you with other relatives who test at the same company – and who may descend from any of your ancestral lines back to about 5th cousins (and possibly further). AncestryDNA and Family Finder are two of the most popular autosomal tests.
Expect to be kept busy exploring your genealogical connection to hundreds of cousin matches. After receiving your initial results, new testers will be added to your match list regularly.
As more people test, everyone’s chance of finding closer matches improves. As you gain experience, there are many third-party sites & tools to utilise.
Exploit your DNA to make exciting new discoveries in your family tree!