IN THIS CHAPTER

Signing up for a DNA primer

Deciding where to test

Searching for DNA sites

It sounds like something right out of a crime scene investigation: You swab your cheek or spit in a tube, send the sample to a lab, the results are analyzed, and presto! You find the identity of someone super-important. However, instead of identifying some master-minded criminal, you find the identity of that long-lost ancestor for whom you’ve been searching. Although the science behind molecular genealogy traces its roots to identifying individuals from crime scenes, it hasn’t advanced to the point where you can simply take the test and watch your entire genealogy unfold. But it can provide valuable evidence that you’re related to a particular family line.

Although deoxyribonucleic acid (DNA) testing is just one of many tools to use in documenting your research, it holds great potential for the future of genealogy. You may be familiar with the use of DNA testing in identifying the remains of Nicholas, the last Czar of Russia, and his family; in debating the last resting place of Christopher Columbus; or in determining the true fate of Jesse James. The methods used in these investigations are the same methods you can use to complement your documentary research.

In this chapter, we provide an overview of how DNA testing works and where you can order tests.

Ask What DNA Can Do for You

You probably have seen the commercials on television. A quick DNA test and now you are ready to go out and buy a kilt or lederhosen or schedule that trip to West Africa. Well, DNA testing can do a whole lot more for your family history research than estimate your ethnicity. Think of DNA testing as another type of record you can use as evidence for your family history— much like a census, vital, or tax record.

Some of the things that DNA testing can accomplish include:

• Determining whether two people are related when one or both were adopted
• Identifying whether two people are descended from the same ancestor
• Discovering whether a person is related to others with the same surname
• Providing evidence for family tree research
• Providing clues about ethnic origin
• Finding out about inherited traits from your family

Four types of DNA testing are currently used with frequency by family historians. As is the case with traditional record types, each type of test is used to gather a specific piece of information. For example, a vital record tells you the birth date of an ancestor. If you want to know how much tax an ancestor paid in a certain location, consult a tax record. In the genetic family history world, the same specialization applies: If you want to know something about a direct-line male relative, you might use a Y-chromosome test. If you want to compare the results of anyone related to you, you might use an autosomal test.

As in any pursuit, individuals who test their DNA can have a variety of objectives. Understanding this can explain why some testers will respond to a message and why some won’t. Here are a few of the common objectives of DNA testers:

• Ethnicity estimation: Some testers just want to know their ethnicity/ancestral origins and may never log into the testing website again. Unfortunately, this can be frustrating for family historians who find a match on a site, only to see that the person who matches hasn’t logged in for two years. Hopefully, the tester will become interested in learning more at some point down the road.
• Family history research: These testers are interested in finding related researchers to provide evidence for their family trees and to discover new sources of documents, family photographs, and stories. Sometimes family historians slide in and out of genetic genealogy tools as they research other record types.
• Mapping ancestors to specific regions on the tester’s chromosome: These testers want to know which ancestor was responsible for contributing genetic material at a certain location on a chromosome. This may be to determine the ethnicity of an ancestor or might be used to determine where an inherited trait or condition came from.
• Reconstructing an ancestor’s DNA: Some testers would like to know what their ancestor’s DNA looked like for ethnicity, inherited traits, or to use a pseudo-result to compare to other current DNA samples to find more descendants of that ancestor. Testers that are conducting this type of research will have to find as many descendants as they can to create as complete a sample as possible.
• Adoption discovery: Adopted testers may be looking for genetic clues to their adoptive parents’ ethnicity or inherited traits, or may be trying to locate biological family members.
• Inherited traits/conditions: Some testers are concerned with the medical aspects of DNA testing. They are interested in the probability that they might eventually develop a particular medical condition.

And, of course, there are those of us that fit into more than one category of the above — that jump from one to another as time allows or when prompted by another researcher.

A Friendly Word of Caution

Before you embark into the world of genetic genealogy, consider a few things: First, by taking a DNA test, you may discover something you would rather not know. For example, some people have discovered that they’re not biologically related to the family from which they’ve always claimed descent. Sometimes this occurs due to a non-paternal (or paternity) event (NPE), also known as misattributed paternity, where the biological father was not the person listed on the birth record. (This may have occurred in the immediate family or in a past generation.) Others have discovered they do not have the racial or ethnic composition that they’ve always identified with. Also, some testing services provide probabilities that a particular disease or medical condition might occur. If you prefer not to know the medical part, you can skip that portion of the results, or take an ancestry-only test.

The second thing to remember is that genetic genealogy is a science, but not an absolute one. DNA test results show the probability that something is true. (Probability is the likelihood that a specific fact or outcome will occur.) Nothing is ever a hundred percent certain. In addition, sometimes (but rarely) mistakes are made by the testing facility, or new research is discovered that changes the way a test result is viewed. This is especially true in the realm of ethnicity estimates. DNA testing for genealogy is still undergoing development and being refined. As long as you can adapt to change and accept new technology, you’ll be just fine in the world of DNA genealogy.

Lastly, it is important to understand that genetics is a sensitive subject and care should be used when using genetic information. You should use the same standards for disclosing information as you would for other records that contain sensitive information. In fact, a group of genealogists and scientists gathered together to draft genetic genealogy standards. The standards can be found at www.geneticgenealogystandards.com. Some of these standards include:

• Consent for a DNA test: This sounds reasonable enough, but there was a case where someone attempted to take a DNA sample from a used coffee cup when an individual refused to test. Also, consent should be given by a parent or legal guardian for minor testers and from a legal representative in the case of a deceased individual.
• Raw data and results: Testers have the right to their test results and raw data, even if someone else paid for the test.
• Terms of service of testing companies: Genealogists and testers should ensure that they understand the terms and conditions of the testing company when purchasing a DNA test.
• Privacy: Genealogists should only test with companies that respect and protect the privacy of testers. Also, it is understood that complete anonymity of testing results can’t be guaranteed.
• Access by third parties: Genealogists and testers should recognize that if results are posted to public sites, then those results can be accessed, copied, and analyzed by a third party without permission.
• Sharing results: Genealogists should respect the tester’s wishes when sharing test results.

Delving into DNA

Some people might think we’re attempting the impossible — explaining how DNA works in only one part of this book. After all, genetic testing is so complex that the information on it can fill many books. However, we feel it is our duty to give you at least a basic introduction to genetic research so that you can use all the technological means available to you when digging for information on your ancestors.

You need an understanding of the terminology and the way the testing process works in order to interpret your test results. If you find that our elementary explanations merely whet your appetite, you can get a healthy dose on the subject with Genetics For Dummies, 2nd Edition, by Tara Rodden Robinson.

Getting down to bases

There’s no doubt about it: DNA is hard to explain. We do our best to keep it simple but informative here. Being a family historian, most likely you’ve taken a research trip to a particular town to find the burial location for an ancestor. When you reached that town, your first stop was probably the local library. Entering the library, you quickly made your way to the reference room. You leafed through the reference room collection, looking for a cemetery index for that area. Finding an index, you located the chapter that contained a list of gravestones for the cemetery where your ancestor is buried. Thumbing through the chapter, you found your ancestor’s name, which is typed with some combination of 26 letters (assuming it contains no special characters and the book is in English).

You can think about the components of DNA like the preceding library. (Figure 10-1 shows a model of the components of DNA.) The basic building blocks of humans are cells that function like little towns. Within each cell is a nucleus, which is the structure that contains all the DNA. This nucleus acts as the library for the cell. Within the nucleus is the genome (the complete set of instructions defining how the cell will operate). You can think of the genome as the reference book collection of the library.

The human genome contains 23 pairs of chromosomes (a total of 46 chromosomes). A chromosome is the container that holds the strands of DNA. Each type of chromosome has a different set of instructions and serves a different purpose. Sticking with our analogy, like a library’s reference collection has several types of reference books, the genome has several types of chromosomes. One pair of chromosomes is referred to as the sex chromosomes. Males have one Y chromosome and one X chromosome in the pair. Females have two X chromosomes in the pair. The remaining 22 pairs of chromosomes (44 chromosomes) are called autosomal chromosomes. Particular sections of a chromosome are called genes. Genes contain specific sequences of information that determine an inheritable characteristic of a human. If a chromosome is a reference book, genes are the chapters in the book.

A particular gene can come in different forms called alleles. For example, the gene for eye color might come in a blue eye allele or a brown eye allele. To use our book analogy, a specific chapter of a book can be laid out in different ways. Alleles would be different layouts that the chapter could have.

Genes are composed of bases, also called nucleotides, which form the rungs of the DNA ladder that hold the DNA molecule together. You find four types of bases: adenine (A), guanine (G), cytosine (C), and thymine (T). When forming the rungs of the DNA molecule, bases attach in only one way. Adenine always pairs with thymine on the opposite strand, and guanine always pairs with cytosine. The attachment of bases is called base pairing. The bases are the language of DNA. You read the sequence of the base pairs to determine the coding of the allele — just like reading the sequence of letters in a book forms a recognizable sentence (see Figure 10-2).

Please understand that our DNA-library analogy is a very simplistic explanation of the molecular parts that are considered in genetic testing. DNA plays a much more complicated role in genetics than what we just covered. However, for the purpose of this chapter, our basic presentation on genetic structure should be sufficient for understanding the broader implications in DNA testing for molecular genealogy. We add further clarification in the upcoming chapters on the DNA testing types so that you get a good idea of what function the test is performing.

Variations in DNA

To help you understand how DNA is passed from one generation to another, we have to take a little trip back to high-school science or health. Our description here oversimplifies the process, but it’s designed to point out things relevant to genetic genealogy. Yes, you guessed it — we are going to have “the talk” about the birds and the bees.

Sexual reproduction is the combining of genetic information from two individuals of different sexes. In humans, this is done by combining the genetic material from a sperm cell with that of an egg cell.

As we mentioned in the previous section, a human cell has 23 pairs of chromosomes for a total of 46 chromosomes. However, for sexual reproduction to work, the total number of chromosomes contributed by each parent needs to be cut in half — 23 chromosomes — so that when the sperm and egg cells unite, there is a total of 46 chromosomes to create the 23 chromosome pairs in the resulting zygote. This process is called meiosis.

Just before meiosis begins, a cell is created with a random collection of half of the chromosomes — one from each pair — from one donor. Also included in the cell is a random set of half the chromosomes from the other donor. For example, for chromosome 1, the contributed chromosome may have come from the mother. For chromosome 2, it may have come from your father, and so on.

The chromosomes in the new cell are then duplicated. The single paternal chromosome 1 is copied into a second paternal chromosome 1, and so forth for all 23 chromosomes. The single maternal chromosome 1 is also copied. The two copies of the paternal chromosome 1 are then attached together with a centromere to form a single paternal chromosome 1 (having double the genetic material). The same happens with the maternal chromosome. By the end of the process, you have two chromosome 1s, one supplied from paternal genetic material and one from the maternal genetic material.

During the first phase of the first stage of meiosis the paternal and maternal chromosome 1s may overlap each other and go through a process of recombination. During recombination, genetic material (alleles) from a portion of the paternal chromosome 1 may be exchanged (or cross over) with the genetic material of the maternal chromosome 1 at the point of overlap.

In later phases of the first stage of meiosis, the paternal and maternal chromosome 1s are pulled to opposite ends of the cell and unravel; the cell divides into two cells. During the second stage of meiosis the cells further divide into four cells. These gamete cells are now ready to be merged with the gamete cells of another sex (see Figure 10-3).

This process of the selection of particular portions of a chromosome pair, in conjunction with recombination, accounts for the variation seen in children from the same parents. As this occurs, during each successive generation, more variation occurs and at some point genetic material from a particular ancestor disappears among all of the selection and recombination.

We come back to this subject in our discussion of how these selections and recombinations affect interpretation of DNA results in Chapter 12 when we focus on autosomal DNA testing.

Family History: Documentation versus Genetics

In the first parts of this book, we talk about ways to create a documented family history. The documentation on a birth record can indicate the father and mother of a particular individual. Census records can map the family relationships of several individuals from a single entry (father, mother, children, in-laws, and so forth). A documented family tree might look like the one in Figure 10-4.

However, when you are looking at a genetic family tree, the individuals involved are a subset of the documented family tree. Everyone in your genetic family tree should be part of your documented family tree. But, not everyone in your documented family tree will be in your genetic family tree (see Figure 10-5).

The reason for this is the chromosome selections and recombinations that we discussed in the previous section. This means unless two siblings were identical twins, they did not inherit the same DNA. One sibling may have inherited DNA from a great-great-great grandfather and another sibling may have not (this means that none of the second sibling’s offspring will ever inherit DNA from that great-great-great grandfather — unless they inherit it from an ancestor of that sibling’s spouse, one who happened to be descended from the same great-great-great grandfather). However, a cousin to the siblings may have inherited the same DNA from the great-great-great grandfather.

We talk more about this in Chapter 12 in our discussion of autosomal DNA, but we thought it was a good idea to let you know this upfront. That way, when you encounter this in your research, you won’t be disappointed.

Testing Companies

These days, a number of companies offer DNA testing. However, for the purposes of this book, we look at the three main companies used by family historians — Family Tree DNA, 23andMe, and AncestryDNA.

Family Tree DNA (www.familytreedna.com) has been offering direct to consumer DNA testing since 2000. The company offers Y-chromosome (Y-DNA), mitochondrial (mtDNA), and autosomal (atDNA) services. The company’s website is home to a variety of surname and location-based DNA projects. Family Tree DNA uses cheek swabs to collect the DNA for analysis.

23andMe (www.23andme.com) was founded in 2006. The company offers an ancestry-only test or a test with health information. Through the test, you can get information on Y-DNA, mitochondrial DNA, and autosomal DNA (along with X-chromosome DNA). The 23andMe test is conducted with a saliva sample.

AncestryDNA (www.ancestry.com/dna) has been offering DNA testing since 2012. The test provides information on autosomal DNA. AncestryDNA offers shared ancestor hints, DNA Circles (uses public family trees to identify cousins), and Genetic Communities (identifies groups of testers that may have descended from a population of common ancestors). The AncestryDNA test is done with a saliva sample.

Selecting the Right Test for You

After you gain a basic understanding of genetics, you may find your curiosity piqued — are you ready to jump right in and gather DNA samples willy-nilly? Slow down! You have more to discover so that you don’t lose time and momentum by submitting your swabs for the wrong types of tests.

Four types of tests are commonly available from DNA testing companies:

• Y-chromosome DNA testing: Humans have 23 pairs of chromosomes. Of these 23, males and females have 22 pairs in common and one pair not in common. In that one pair, males have one X and one Y chromosome, whereas females have two X chromosomes. The Y-chromosome DNA test explores the Y chromosome in this uncommon pair of chromosomes. As you might suspect at this point, this particular test is available only for men because females do not carry the Y chromosome. However, just because you — the reader — might be female, don’t fail to read the following section on Y-chromosome DNA testing. You can always have a male relative (such as your father, brother, uncle, or cousin) take this test for you to discover the hidden secrets in your familial Y-DNA.
• Mitochondrial DNA testing: The mitochondrion is considered by some to be the “power plant” of the cell. (Remember, the cell is the basic building block of the human body.) It sits outside the nucleus of the cell, and it contains its own distinct genome — that means its genome is separate from the genome found in the nucleus of the cell. This distinct genome is known as mtDNA in genetic testing. The mtDNA is inherited only from the female parent, is passed to all offspring (male and female), and mutates (or changes) at a slow rate over generations. All of these aspects of the mtDNA make it good for identifying genetic relationships over hundreds of generations.
• Autosomal DNA testing: Autosomal DNA consists of 22 pairs of non–sex-specific chromosomes that are found in the cell nucleus — this means that they don’t contain the X or Y chromosome. Autosomal DNA is found in males and females and is the part of the DNA responsible for characteristics such as height and eye color. This DNA is inherited from both parents. Autosomal testing, also called admixture or biogeographical testing, is used to determine paternity, indicate ethnicity, and diagnose potential health problems.
• X-chromosome DNA testing: As we mention earlier, males have one X and one Y chromosome, whereas females have two X chromosomes. This test looks at the mixture of the X chromosomes inherited over several generations.

Given the complexity of genetic research, we expect the tests to be complicated as well. Hence, each test warrants its own attention. In the next two chapters, we explore them in a little more depth.

Finding Helpful DNA Sites

Within this chapter, we were able to cover only the tip of the iceberg in using DNA testing for genealogical purposes. Some websites can provide additional information to help you decide whether DNA testing is useful for your research or to keep abreast of the current developments in DNA research.

If you’re looking for some basic information on using DNA testing in genealogy, see the International Society of Genetic Genealogy Beginners Guides to Genetic Genealogy page at https://isogg.org/wiki/Beginners%27_guides_to_genetic_genealogy. There is a lot of other information on genetic genealogy on the website, so you might want to check out their Wiki pages.

Because DNA testing methods and capabilities change on a frequent basis, it’s a good idea to consult some sites that provide updates on the technology and issues related to using the technology. A few sites to consult include

• Genealogy-DNA mailing list archives: http://lists5.rootsweb.ancestry.com/index/other/DNA/GENEALOGY-DNA.html (You can also subscribe to the mailing list from this page.)
• Genetic Genealogist blog: www.thegeneticgenealogist.com
• segment-ology: https://segmentology.org/