Genetic genealogy combines traditional historical and genealogical research with DNA analysis. Its purpose is to discover how individuals are related and determine which ancestors they have in common. This helps extend and confirm family trees, especially when the paper trails are incomplete, incorrect, or unavailable.
Find Relatives The first function of genetic genealogy is to find previously unknown relatives. The testing company will compare your DNA with everyone else who has already taken the same test and will continue to compare you with new people who take that test for years to come. You will get a changing list of people who share significant amounts of DNA with you. All but the most distant matches must share a common ancestor. Some of your matches will have online family trees. You can also contact matches to begin a dialogue. Either way, you will learn something new about your family tree.
Confirm Relationships The second function of genetic genealogy is to measure how much DNA two people have in common. This can confirm or disprove a suspected relationship out to the second cousin level and sometimes further out. The amount of shared DNA can be expressed in percentages or in centimorgans (cMs).Estimated relationshipObviously, this function is especially critical for adoptees who believe they have found a close biological relative. But other questions can also be answered, such as: are two people full siblings or half-siblings? Are twins identical or fraternal? And is the man who raised me really my biological father?
Ethnicity results from MyHeritage DNAEstimate Ethnic Origins The third function is to learn what mix of ethnicities we inherited from our ancestors. This science is new and evolving. These reports can be fascinating, and their accuracy is improving over time, but they are still just estimates and should not be taken as scientific fact. They can help confirm known ethnic origins, and shared ethnicity results can sometimes provide additional clues about how you may be related to a given DNA match.
Determine Ancient Ancestral Lines The fourth function is to determine your ancient ancestry through haplogroups in your direct paternal and maternal lines.
The Y-DNA test traces paternal ancestry through a male person’s father’s father’s father and so on. Unless there is an adoption or other name change, the surname can remain unchanged down the direct paternal line for many generations.
Only men have a Y chromosome to test. But women can test a suitable male relative such as their brother, their father, their father's brother, or a son of their father's brother. By selecting suitable test subjects, you can explore many paternal lines in your family tree.
If two men take a Y-DNA test and show up as a match, we know that their direct paternal lines must intersect with a single common male ancestor. In other words, if we go up one man’s father's father's father's line and the other man’s father's father's father's line, they must, at some point, include the same man.
The main limitation of Y-DNA testing is that it can't tell us with any certainty how far back that common ancestor lived. He could be just a few generations back, or he could have lived hundreds of years ago.
Mitochondrial DNA testing
MtDNA inheritance
We all inherit mitochondrial DNA from our mothers. But only women pass it on. This test can help you trace and confirm maternal lines. In practice, it can be more difficult to apply than Y-DNA testing, since in many cultures, the surname changes at every step down the maternal line.
Looking at your family tree, you can think of these first two test types as narrow and deep. They are narrow because each test traces just a single line through your tree. They are deep because the common ancestors responsible for your matches may be recent or may have lived hundreds of years ago.
Autosomal DNA testing
Transmission of autosomes from grandparents to three siblings
Unlike the first two test types described as narrow and deep, autosomal DNA testing is wide but shallow. It is wide because it can uncover cousins from any branch of your family tree. Yet it is shallow because it can only go back consistently about 5-7 generations.
That's because autosomal DNA is a mix inherited from both parents. The amount of DNA from your ancestors gets cut in half after every generation. As a result, the DNA from more distant ancestors does not stand out.
Autosomal DNA testing is the least expensive of the three test types and has the largest databases of users. The MyHeritage DNA test is an autosomal DNA test.
DNA testing procedure
Regardless of the test type or the company doing the test, the testing procedure involves the following steps:
Order your test kit online from the testing company's website
Receive a test kit by postal mail
Collect your sample using cheek swabs or spitting into a tube
Return your DNA sample by mail
Receive a notification by email when your results are ready
Log into your private password-protected account to view the results
NOTE: The method usually doesn’t matter unless the subject cannot easily spit saliva into a tube. Here are four examples where cheek swabs work better.
