Research and Verify Your Ancestors Using Genetic Genealogy (DNA)
HOW TO…
Learn about DNA and its place in genealogical research
Discover the difference between paternal testing, maternal testing, autosomal testing, and the results
Learn about test processes and results
Determine what tests are appropriate for you and other family members
Learn about genetic testing services
Join a DNA surname project on the Internet
Learn more about genetic genealogy
You’ve probably read or heard other genealogists talking about using DNA to assist with their research. One of the most recent additions to the genealogist’s toolkit is genetic testing. Like learning how to use the Internet and databases, you’ll want to learn about DNA and genetic testing in order to understand it and apply it in your own research. Because this chapter cannot possibly address everything about genetic genealogy, I’ll discuss some basic concepts and then refer you to other books at the chapter’s end that will provide you with an in-depth understanding.
We all have physical traits that distinguish us from one another. You’ve often heard the comment that someone has his mother’s eyes, her father’s hair coloring, or some other physical attribute. We know that genetics, the science of biology and heredity, plays a central role in how we are formed. Our genes provide the template for our physical development, from the single-cell fertilized egg to the human form that we become. The basis of this genetic template is DNA.
Learn About DNA and Its Place in Genealogical Research
DNA is an acronym for deoxyribonucleic acid, a chemical that is the blueprint for every cell in all living organisms and in some viruses. DNA molecules store the information and instructions for all the components of cells. DNA carries the genetic information, called genes, that is involved with how the entire organism is formed.
You may have heard the structure of DNA referred to as a “double helix.” DNA physically consists of two long strands of organic material called nucleotides. The nucleotides are formed from sugars and phosphate groups that are joined together. These long strands run in opposite directions and form the twisted double helix. One of four types of molecules is attached to each sugar in each strand, and these molecules are called “bases.” The sequence of the bases is the coding that determines the genetic coding for each cell. The coding is replicated into ribonucleic acid, known as RNA, a single strand of nucleotides.
DNA is organized into structures called chromosomes, and these building blocks are duplicated before cells divide and replicate themselves. All of this information is essential to the creation of life. Scientists have been working for decades to decode the genetic sequences and understand the function of each gene. The Human Genome Project began in 1990 with the goal of identifying all of the human genes and studying their physical structures and their functions.
Although this is a relatively simple description of DNA, it will suffice for the rest of the discussion in this chapter. I have also included at the end of the chapter a concise bibliography of reference books that can help you learn even more.
Both genetics and genealogy focus on heredity:
• Genetics is a branch of biology that concentrates on the scientific study of the heredity of an individual organism’s physical traits. It also is used to demonstrate relationships between individuals.
• Genealogy is the study of families and includes tracing the lineage and history of families and demonstrating kinship and history. It seeks to establish proof of relationships from one generation to another.
As you can see, the two research disciplines share a somewhat common goal. DNA has been used in medical and forensic applications for quite some time. Amniocentesis is a method in which a small amount of a pregnant woman’s amniotic fluid is removed and tested. It is an important procedure used to diagnose chromosomal irregularities and infections and employs genetic testing. Paternity tests also use DNA to confirm or refute the relationship of a man to a child. We’ve seen many episodes of television dramas in which DNA evidence has been used to identify a body, to determine the relationship between individuals, or to link a suspect to a crime scene or a victim.
DNA in your genealogy research can similarly be used to prove or disprove relationships between individuals and family groups. While not as precise as forensic DNA analysis, modern DNA testing for genealogical purposes has advanced to include more genetic marker tests. These provide a broader range for comparison with other people’s test results.
There are three timeframes with which DNA testing can help genealogists:
• Modern Era This period covers the last 500 years, which encompasses the time when the first surnames began being used in England and elsewhere.
• Historical Era This period includes the time before surnames were commonly used; generally speaking, before the year 1500 A.D. back to the beginning of written history.
• Ancient Era This period extends backward before the historical era. This is often referred to as the period of “deep genealogy” or “deep ancestry” when it is possible only to trace migrations of groups.
The modern era is the period in which you are most likely to be able to achieve the most value from DNA testing in your genealogical research. However, some kinds of testing can also identify your paternal line or maternal line haplogroup. Haplogroups are the main branches of the human genealogical tree, and they consist of haplotypes. Haplotypes are closely linked genes and genetic markers that are shared by a closely related group of people. These people typically are from a specific geographical area and/or part of the same ethnic origin. Haplogroups correspond to early human migrations between distinct geographical regions. Your haplogroup is indicative of your deep ancestral origin. Figure 13-1 shows an example of a haplogroup report from Family Tree DNA.
FIGURE 13-1 Sample of haplogroup results from Family Tree DNA
Discover the Difference Between Paternal Testing, Maternal Testing, Autosomal Testing, and the Results
It is important to know that humans, as well as most other mammals, have one pair of sex-determining chromosomes in each cell. Males have one Y chromosome and one X chromosome, while females have two X chromosomes. The Y chromosome is present only in males and can therefore reveal information only about the paternal line. The test for the Y chromosome is referred to as a Y-DNA test. Figure 13-2 shows the results of a Y-DNA test from Family Tree DNA.
FIGURE 13-2 Sample of Y-DNA test results from Family Tree DNA
For a Y-DNA test, the test determines the values of a set number of markers, and the resulting values can be compared against other people’s results. The Y-DNA test uses highly variable repeat sequences that can identify closely related individuals or differentiate between unrelated individuals. It also is used to study mutations in the marker values. Both the similarities and the mutations help determine the number of generations backward that there may be to reach a “most recent common ancestor” (also referred to as the MRCA). The mutations occur at a comparatively regular rate, and these changes can be used to project statistically the number of generations between you and the MRCA that you share with another person.
A Y-DNA test can reveal that a man is related in some degree to other males—with the same surname or not. It indicates that there is a common male ancestor, but there may be no way to determine exactly how many generations back that the MRCA lived. The value, however, is in comparing your Y-DNA test results with other people’s results. We’ll discuss this later in the chapter when we cover DNA surname projects.
Mitochondria are structures within cells that convert energy from food into a form that the cells can use. The mitochondria contain a small amount of their own DNA. This genetic material is known as mitochondrial DNA, or mtDNA. This mtDNA is passed only from mother to child, and there is usually no change from parent to child. It is therefore a powerful tool for tracing ancestry through the female line.
The mtDNA test allows you to undertake research into the records of your mother’s maternal ancestors. This can be a daunting task. However, the mtDNA test results can be used to definitively confirm your research and the relationships in your maternal lineage (see Figure 13-3).
FIGURE 13-3 Sample of mtDNA test results from Family Tree DNA
The rest of your DNA, the part that isn’t the sex-determining chromosomes and the mitochondrial DNA, represents a mix of DNA from both your parents, and is known as autosomal DNA. In recent years, this has become the most popular type of DNA testing, because it can match so many potential cousins on all ancestral branches of your family. An autosomal DNA test is most effective, however, when people share comparatively recent common ancestors.
It is important to know that we inherit, on average, 50 percent of the DNA from each of our parents. Since our parents also inherited, on average, 50 percent of each of their parents’ DNA, we can be certain that the DNA we inherited from our parents contains markers reflecting approximately 25 percent of our grandparents’ DNA. The autosomal DNA test is used to study the marker code values of those 22 additional pairs of chromosomes, and then it is possible to compare those values against other people’s test results to check for cousinship. First- and second-cousin relationships are almost certain to show up. The percentage of DNA from great-grandparents, great-great-grandparents, and more distant ancestors diminishes in each successive generation. Therefore, matches with third, fourth, and more distant cousins are still possible, but they are less likely than matches to closer relatives.
To summarize, there are three common types of DNA test available to assist in your genealogical research:
• Y-DNA Test This is a test available only for males to help determine their direct paternal line.
• mtDNA Test This is a test available to anyone (male or female) to help determine their direct maternal line.
• Autosomal Test This is a test available to anyone (male or female) to help determine all ancestral lines, but back only to a limited number of generations.
Test Processes and Results
You begin by deciding which DNA test you want (usually either Y-DNA, mtDNA, or autosomal DNA) and then investigating the companies that provide that type of test. In the case of a Y-DNA test, another consideration will be the number of genetic markers you want tested and reported on, because the price of the Y-DNA test is based on the number of markers tested. The more markers that are tested, the greater the accuracy in matching the DNA test results of other people. Once you have made these decisions, you can then order a test kit from the DNA testing company. For some testing companies, such as Family Tree DNA, the kit consists of several sterile swabs, an envelope that you seal and label, and a return mailer. The physical test consists of rubbing the swabs inside your mouth and then placing them into vials. Your oral epithelial cells and saliva contain DNA, and it is that which is captured on the swab. For other testing companies, such as Ancestry.com, you fill a small vial with your saliva, but the rest of the process is similar. You return the vials to the testing company and, after some weeks, you receive your test results online.
Genetic genealogy gives genealogists a means to check or supplement the historical record with information from genetic data. It can be used to help resolve gaps in your documentary research. However, there are other possibilities. A positive test match with another individual may
• Validate your existing research
• Suggest geographical areas for genealogical research
• Help determine the ancestral homeland and/or ethnic origin
• Discover living relatives
• Confirm or refute possible connections with other individuals and/or families
• Prove or disprove theories concerning ancestry
As you can see, Y-DNA and mtDNA tests can trace ancestry on the paternal and maternal lines, respectively. The autosomal DNA test, however, can take your research into a more precise area. It also will provide you with matches from both sides of your family at once.
You should know that there is resistance to DNA testing by some individuals. The reasons may include
• Uncertainty about which testing company to use
• Cost of the test
• Quality of the testing
• Variation in the number of markers tested by the companies
• Privacy issues
• Identity theft concerns
You may want to seek the participation of other relatives to help expand your genetic genealogy research. Many genealogists encourage cousins, aunts, and uncles to submit DNA test kits, even offering to pay for the testing in order to gather more sample data. You may want to consider this incentive approach in order to extend the range of your genetic research.
Learn About Genetic Testing Services
There are many commercial DNA testing services available. For each service you are considering, you will want to conduct research about the types of tests and the number of markers tested, the price of the tests, and any affiliations they may have with other companies and/or with surname DNA projects on the Internet. You may, in fact, be able to obtain a lower price as part of a surname group, discussed in the next section. Prices differ between the different types of testing, and prices also may vary between testing services. Some of the companies offer a combination of tests together in a bundle at a package deal price. You want to select a testing service whose results are specifically used for genealogical purposes. A DNA paternity test kit or a forensic DNA testing service is not going to be of value to your genealogical research.
The following table lists the three major DNA testing services for genealogists in the United States:
Join a DNA Surname Project on the Internet
Genealogists who have had their DNA tested want to locate genetic matches to other researchers. This is particularly true of those who have had their Y-DNA tested and are seeking matches with others with the same surname and those who have had their autosomal DNA tested and wish to connect with cousins. A surname DNA project is the ideal place to make connections with other researchers.
A surname project is a genetic genealogical project in which the results from Y-DNA testing are used to trace male lineage. Surnames are passed down from father to son in many cultures, and Y chromosomes are passed from father to son with a predictable rate of mutation. People who share the same surname can use Y-DNA testing to determine if they share a common ancestor within recent history. It is certainly possible for persons with a different surname to share the same Y-DNA test results. Don’t jump to any conclusions, however. Yes, there may have been an illegitimate child, but other factors may also account for the discrepancy. There may have been a change of surname due to adoption; a man may have taken his wife’s name; frequent misspelling of an earlier surname may have resulted in a man taking another surname; a surname may have been changed by a male immigrant in order to “fit in”; or a nickname or alias may have been used and was then taken as the surname.
The results of a Y-DNA test checks the values of Y-chromosome markers. Depending on the number of markers tested, the results can be compared to someone else’s results and can reveal whether the two individuals share a common male ancestor. The number of markers tested and the number of matches at those markers can help determine the range of generations until their MRCA would be expected. Let’s say that two men are tested using 37 genetic markers. If the two tests match exactly on 37 markers, there is a 50 percent probability that the MRCA was no more than two generations ago and a 90 percent probability that the MRCA was no more than five generations ago. A further comparison with other persons’ test results might indicate a familial relationship.
A DNA surname project takes the comparison another step. By joining such a project on the Internet, you not only share your test results, but also provide documentation of that surname in your ancestry back to your earliest known male ancestor in that surname line. The administrator of the project adds your test results into a grid that allows for easy comparison of each marker’s value with that of other people. The name of each participant’s earliest documented ancestor is included, as is the haplotype. The results are typically grouped together by haplotype in order to create clusters of more closely related individuals. You can make contact with other researchers, usually with the project administrator acting as intermediary to help protect each person’s identity and privacy until both researchers indicate their desire to communicate directly. You can then share more detailed genealogical information and collaborate to further one another’s research.
Learn More About Genetic Genealogy
There is obviously much more that you can learn about genetic genealogy and using DNA test results in your research. There are several books available on the subject. I personally recommend the following titles:
• Aulicino, Emily D. Genetic Genealogy: The Basics and Beyond. AuthorHouse, 2013.
• Dowell, David R. NextGen Genealogy: The DNA Connection. Santa Barbara, CA: Libraries Unlimited, 2014.
• Pomery, Chris. Family History in the Genes. Kew, Richmond, Surrey, UK: The National Archives, 2007.
• Smolenyak, Megan, and Ann Turner. Trace Your Roots with DNA: Using Genetic Tests to Explore Your Family Tree. Emmaus, PA: Rodale, Inc., 2004.
Another excellent place to learn more about DNA is the How-To DNA blog at http://howtodna.com. This is a multimedia blog that includes videos, podcasts, and other types of postings to help you learn about genetic genealogy and how to understand and use the DNA test results. The author is Dr. Blaine T. Bettinger, professional genetic genealogist and author of the long-running blog, “The Genetic Genealogist” (http://www.thegeneticgenealogist.com).
The possibilities offered by DNA testing are increasing and improving each year. You will want to incorporate genetic genealogical research into your research toolkit, and gain another strong research facility for your family history.