genetic genealogy: DNA testing

genetic genealogy: DNA testing

Genetic testing is quickly becoming vital for the family genealogist. At what point should you have your DNA tested, and which DNA test is most useful for further defining your family history?

The utilization of both genealogical research and DNA testing will produce concrete results more quickly than using only one method. Family records can be subjective in nature and prone to errors (i.e. transcription error, non-parental events). DNA testing can provide a new pathway to uncovering your familial line(s), strengthening (or eliminating) previously researched documents. FAIR WARNING: Investing in DNA testing can run into the hundreds of dollars. The more tests you take, the larger the bill.

There are generally three kinds of tests offered: yDNA, mitochondrial DNA and autosomal.

yDNA testing is used to define a person’s direct male lineage. Since most surnames are patriarchal in nature, matching yDNA test results with your father’s paternal records are usually accurate. The limitations of yDNA testing is that it only tests one direct male line only, your father, his father, his father’s father, and so on. NOTE: For a woman to see her paternal lineage, she will need to have her father, brother, father’s brother, father’s father, or male cousins on her father’s side have their DNA tested. Women have an XX chromosome. Men have XY chromosome. It is the “Y” chromosome that defines the male line, hence the name yDNA.

An mtDNA test identifies the origins of your maternal line (your mother, your mother’s mother and so on). Considering that most records are patriarchal, matching your mtDNA results to your maternal records can be difficult. This test is more valuable for understanding your genetic history and where your maternal line originated geographically. the ‘mt’ in mtDNA stands for mitochondrial, which is carried on the X chromosome. Because a man has an X chromosome, he can have his mtDNA tested.

Autosomal testing was introduced at many DNA testing facilities (ex. Family Tree DNA; Ancestry.com, 23andMe) in 2010. Autosomal testing looks at the remaining 22 pairs of chromosomes, so either a male or female can take this test. These 22 non-sex chromosomal pairs are inherited from both parents. The purpose of autosomal dna testing is to help the individual to trace all of their ancestral lines at least 5 or more generations deep. IMPORTANT: Complete as much of your family tree as possible. The more surnames you can identify through your family history research, the more valuable the autosomal test becomes. Your autosomal test results and the surnames that you provide are entered into a database and compared against fellow genealogist who’ve done the same. Here’s the exciting part! Distant and close cousins from around the world will begin to appear on your list. As more people have their DNA tested, your list of relatives will grow!


Find out where your family came from. Which might explain why you are the way you are.