DNA 101 EXPLAINED
RESOURCES
The subject of DNA is complicated, controversial, and has evolved a lot more than you probably learned in your high school biology class. The advances in DNA technology are exponentially growing and understanding the importance of DNA testing and sharing may be more than you realized. It's my hope that I can educate you and encourage you to get your own DNA testing done. Then learn what to do with it afterward.
DNA 101
According to The Genetic Geneaologist, here is what basic DNA testing can do for you:
INDICATES THAT YOU AND ANOTHER PARTICIPANT SHARE A COMMON ANCESTOR:
f two participants closely match on their test results this is an indication that they share a common ancestor. Just how strong this connection depends on the strength of the DNA match.
PROVIDES A ROUGH IDEA OF HOW BACK YOUR COMMON ANCESTOR LIVED.
This depends on the strength of the DNA match plus the paper trails.
SUPPORTS EVIDENCE THAT SUSPECTED LINES ARE CONNECTED
While DNA testing can not prove that suspected lines are connected, it can provide evidence to support it, especially when supported by a paper trail. How strong this evidence is depends on the paper trails and the strength of the DNA match.
PROVIDE PROOF THAT TWO INDIVIDUALS OR LINES ARE NOT CONNECTED
No matter how good the paper trail may be, if there are too many DNA mutations, they can not be related.
IMPORTANCE OF DNA TESTING BEYOND OURSELVES
Over the past five years or so, researchers have conducted ever-more and ever-larger GWAS (genome-wide association studies) identifying thousands of SNPs linked with personality, intelligence, depression, and a host of other psychological traits and disorders (and, outside of psychology, with physical traits and illnesses, like obesity and heart disease, too).
Polygenic risk scores, then, are a way to take the information from GWAS and apply them to an individual. “Polygenic” means “many genes,” and that’s what these risk scores include. Once you genotype a person’s DNA, you can comb through it for SNPs that have—through large GWAS—been associated with a particular trait. Then you simply add up the number of these SNPs in the DNA, while weighing them appropriately because some SNPs are more strongly associated with a trait than others. The resulting number is the person’s polygenic score for that trait. It’s usually expressed as a percentile—as in, this person is in the 70th percentile of genetic risk for developing schizophrenia, for example, or the 90th percentile for academic achievement.
Winerman, L., 2019. What can we learn from our DNA?. [online] https://www.apa.org. Available at: <https://www.apa.org/monitor/2019/03/cover-dna> [Accessed 26 July 2022].
WHY GET A DNA TEST DONE?
Genetic ancestry testing can provide insights into the geographic origins of an individual's ancestors, as well as some information that can aid in the assessment of risk for some heritable conditions. The accuracy of testing is limited by the migrations and mixing of populations over time.
WHAT TEST SHOULD I GET?
This varies somewhat whether you are male or female and your main goal with getting your DNA testing. A Y-DNA test for example is only for males. It shows the lineage of the father-to-son relationship. This is a useful tool when breaking down paternal brick walls and surname research.
Autosomal DNA (atDNA) is the most common testing done by commercial companies such as AncestryDNA.
Especially with adoption or unknown parentage cases I recommend first testing with AncestryDNA, then transferring the results to Family Tree DNA, MyHeritage DNA (free), and Gedmatch (also free). Then purchase a Promethease.com report for health information. When you have more funds to invest, then test with 23andMe. That will put you in all of the databases to match with others and be able to use all of their tools.
Lee, Andrew; Lee, Devon Noel. DNA Q and A: Real Questions from Real People about Genetic Genealogy (p. 17). Kindle Edition.
ETHNICITY RESULTS
Each company compares your genetic data to a reference population and attempts to match up segments with those in the reference sets. Each company has its own algorithms and reference sets. It is no surprise that the results vary from each business, even when analyzing the same raw data. Sometimes the variance is minor, and sometimes it is significant.
WHAT ARE SEGMENTS?
Each person has a set of chromosomes from their mother and another set from their father. Before a chromosome is passed on to you, it shuffles places. This reshuffling mixes the DNA from your father’s parents or your mother’s parents. Thus the chromosome you receive from dad is recombined DNA from grandma and grandpa. Across your 23 chromosome pairs, Dad's chromosome pairs with a similarly recombined chromosome from Mom.
Ultimately, your DNA is unique from what your mother, father, and grandparents had. However, you have pieces of DNA that you share with your parents and grandparents. Those genetic pieces are called segments.
Whenever you genetically match with other relatives, companies find similar segments of DNA between each of you which indicate a shared relation. In short, a segment is a piece of DNA that two or more people inherited from a common ancestor.
Lee, Andrew; Lee, Devon Noel. DNA Q and A: Real Questions from Real People about Genetic Genealogy (p. 8). Kindle Edition.
WHO SHOULD GET A DNA TEST FIRST?
Test oldest first is always best unless you have a specific problem you are trying to solve and have identified others who could potentially solve that problem.
1) When they die, their DNA is gone.
2) They have all of the DNA that their descendants have and reach further back on the genetic family tree than younger individuals.
3) The more generations that test, rather than the more individuals within a generation, increases the length of matching segments between each generation. Longer sequences of matching DNA increase the chances of finding additional relatives.
4) Since Y-DNA and Mitochondrial DNA are passed down without going through recombination, there is no benefit between testing older people or younger people with these tests. There is still the remote possibility a mutation occurred between your grandmother and you. In which case, you would want your grandmother tested to have a better chance of matching with distant relatives.
After collecting samples from every parent and grandparent, testing children and grandchildren yield no additional genealogical information. However, the results do provide an anchor for triangulation. It also confirms that you really are your father's child (sometimes you aren't!).
Lee, Andrew; Lee, Devon Noel. DNA Q and A: Real Questions from Real People about Genetic Genealogy (pp. 16-17). Kindle Edition.
I GOT MY TEST RESULTS, NOW WHAT?
Download Everything
The easiest way to download your ethnicity results is to look for the Print button available from all major providers and then choose to Print to PDF, an option available on many computers.
You’ll also want to download your match list. This will not only allow you to have a backup but will also make it easier for you to use these results in your research.
Finally, download a copy of your RAW DNA file. This will be needed if you plan to take advantage of free and low-cost ethnicity reports and tools from other providers.
As with all of your genealogy files, do make sure to back everything up in a trusted online space.
Educate Yourself
Education is very important if you want to use your results to understand more about your family’s past and grow your family tree.
To start educating yourself, read some of the information in the articles in our Genetic Genealogy section here. Then consider signing up to take a course that will guide you through the process of using your results in your research. Family History Daily’s courses open again this fall with an expanded DNA section.
And, of course, there are numerous high-quality educational materials elsewhere online – some free and some at a cost. Each testing provider offers its own tutorials, and places like GEDmatch offer education materials as well. The FTDNA forums are a wonderful place to ask questions if you need some help from the testing community.
You’ll also want to check out these established sites, which are some of our favorites.