DNA testing can connect you with living cousins, steer your research away from dead ends and lead your ancestral investigations in promising new directions. But trying to figure out which test (Y-DNA? mtDNA?) will provide the answers you seek can get confusing. A genetic test costs anywhere from $100 to $1,000, so you don’t want to waste money on the wrong one.
Learn more about how to use DNA testing in your genealogy research from genetic genealogy expert Blaine Bettinger in our Intro to DNA Crash Course video presentation, available in Family Tree Shop.
The Y chromosome is passed virtually unchanged from father to son, just like a surname. That’s why genetic genealogists use portions of the Y chromosome (also called Y-DNA) to trace paternal lineage—what’s listed on the top line of a pedigree chart (see the illustration on page 53). A man today should have the same Y-DNA (and theoretically, the same surname) as his father, his father’s father, his father’s father’s father, and so on. (Exceptions to the DNA-surname link occur in cases of adoption, infidelity or the occasional genetic mutation—more on this later.) Geneticists can determine whether two men, particularly those with the same surname, are related by comparing their Y-DNA. If they share an ancestor, their Y-DNA test results will be identical or nearly identical.
Since a woman doesn’t have a Y chromosome, she must turn to someone with the same Y-DNA as her biological father to trace her paternal lineage. That means her father, brother, uncle (on her father’s side) or male cousin (the son of the father’s brother) would need to take the test. My maiden name is Eisenstodt. If I wanted to participate in an Eisenstodt/Eisenstadt surname study, I’d have to ask my father or brother to take a Y-DNA test. I’d then compare the results to those of men in the study.
The problem with Y-DNA and mtDNA is that they can tell you about only a small section of your family tree: the top and bottom lines of your pedigree chart, not the branches in between. To fill in the middle branches, geneticists use autosomal DNA—from the other 22 pairs of chromosomes called autosomes, which make up 99 percent of our genetic composition.
The Y chromosome and mtDNA remain largely unchanged as they’re passed from generation to generation, but mutations do occasionally occur. Just as your fourth-great-grandfather might’ve changed the spelling of his last name, his Y-DNA might have changed, as well. Genetic mutations are passed down from generation to generation. Like surnames, they distinguish one family group from another.
Ready to apply what you’ve learned to real-world research problems? You’ll get the most bang for your buck if you start by identifying the specific question you want answered. That’ll determine what type of test you should order and who should take it—you or a relative (see the sidebar on pages 50 and 51 for sample scenarios). Pricing depends on the number of markers tested—the more markers, the higher the price—as well as on the analysis you’d like done. For instance, you can ask for a haplogroup analysis that tells you what genetic group your ancient ancestors belonged to.
To order your own testing kit, call one of these companies, or visit their Web sites, where you’ll find answers to frequently asked questions.
23andMe, [email protected]
African Ancestry, (202) 723-0900
Ancestry DNA, (800) 958-9124
DNA Heritage, (866) 736-2362
DNAPrint Genomics, (941) 366-3400
DNA Testing Systems, (480) 292-9820
Family Genetics, +44 (161) 3559320
Family Tree DNA, (713) 868-1438
Familybuilder, (713) 868-1438
Genelex, (800) 523-3080
GeneTree, (801) 313-8122
There are ways to get around the gender limitations of genetic testing. Here are some common research questions and how you can attempt to answer them, whether you’re a man or a woman.
MAN: Both of you should get your Y-DNA tested and compare the results.
WOMAN: Assuming your maiden name is the one your co-worker shares, ask a male relative with that name (your father or brother, or your father’s brother or his son) to get his Y-DNA tested. You’d then compare your male relative’s test results to your co-worker’s. If your married name is the same as your co-worker’s, have your husband take the Y-DNA test.
You and your female co-worker have the same last name. Are you related?
MAN: If your co-worker’s maiden name is the same as your last name, you should get your Y-DNA tested, and she should ask a male relative with that last name to get his Y-DNA tested.
WOMAN: If your maiden names are the same, then each of you should ask a male relative with that name to get his Y-DNA tested.
Your mother’s maiden name is Wheeler. You want to know if her father was related to other Wheelers involved in a surname study you heard about.
MAN and WOMAN: Your grandfather didn’t pass down Y-DNA or mtDNA to your mother, so niether she nor you can get tested. If your grandfather’s living, he could take a Y-DNA test, which you can compare to results in the study. Your grandfather would’ve given his Y-DNA to a son (your uncle), so your mother’s brother could take the test. If this uncle had sons (your cousins), they share his Y-DNA and could get tested.
According to family lore, you have an American Indian ancestor on your father’s maternal line.
MAN and WOMAN: To confirm this story, you’d need to have your father’s mtDNA tested—not your own, since your father didn’t pass down his mtDNA to you or your siblings. You also could have one of your father’s siblings tested, since his mtDNA is identical to theirs. If your father has a sister, she would’ve passed down that same mtDNA to her children, so they could be tested. And if your father’s sister has a daughter, any of the daughter’s children can be tested.