Genetic Counseling

Genetic Counseling

Forget the scientific jargon — you want to know how genetic genealogy applies to your real-life research situations. Our panel of experts gives you the skinny on using DNA to solve 10 common family tree quandaries.

In the genealogical world and beyond, genetic genealogy is touted as the newest frontier in family tree research. You’re sure your DNA holds the answers to some of your pedigree questions — but all the science stuff leaves you with a big headache.

Put down that bottle of aspirin. You don’t have to be a genetics genius to use DNA testing for your family history research. To let you skip the advanced biology lesson and get right to the results, we consulted four experts who’ve heard it all from would-be genetic genealogists such as yourself: Emanuela (Lou) I. Charlton of DNA Print Genomics <www.dnaprint.com>; Ann Turner, founder of the Genealogy DNA mailing list (you can sign up at <lists5.rootsweb.com/index/other/DNA/GENEALOGY-DNA.html>) and co-author of Trace Your Roots With DNA (Rodale); Scott Woodward, head of the Sorenson Molecular Genealogy Foundation <www.smgf.org>; and Gina Paige, president and co-founder of African Ancestry <www.africanancestry.com>.

Here, they explain what answers DNA can provide to 10 familiar pedigree problems. As you’ll learn, DNA isn’t a magic wand: You can’t take a test and — poof! — fill in entire branches of your family tree. But it’s a good complement to traditional research that lets you reveal your genetic makeup, learn whether you’re related to someone, find out your ancestors’ ancient homeland and prove (or disprove) family lore about famous lineages. So avoid that migraine and let the experts show you how to make the most of your genes.

There are several distinct branches of the Fenstermaker family in America. We think they all must link to the first immigrant, Friedrich Fenstermaker, who came in the early 1800s, but we can’t find proof. What DNA test would help us solve this problem?

TURNER: Y-chromosome testing on Fenstermaker males can confirm (or rule out) a connection among them, but it cannot pinpoint exactly how they are linked.

CHARLTON: Only a direct test between your DNA and that of another modern Fenstermaker — an STR paternity/sibling-type test — could definitively show a relationship between the two of you. For that, you’d have to have a sample of the other person’s DNA. This is usually obtained from a buccal [cheek] swab, but can come from other sources such as the roots of several hairs from his head.

WOODWARD: You don’t have absolute proof. It’s easy to eliminate relationships, but very difficult to prove relationships. I’d draw the pedigrees out as deep as possible, identify those branches that don’t have records documenting a path back to a common ancestor, take the terminal ends [modern male-line descendants] of each one of those branches and collect a DNA sample from each. Get a complete Y-chromosome profile and lay those out on the pedigree. If they share the haplo-type, then you know they share a common paternal ancestor.

If each man who took a DNA test was related to the first immigrant, they would all have a shared haplotype. If the Y haplo-types differ between the different branches, then you can say Friedrich Fenstermaker isn’t the common ancestor.

My mom is sure we’re related to Confederate Gen. Robert E. Lee. How can we prove it?

WOODWARD: Right now, the only test to answer that is the Y-chromosome test.

TURNER: First of all, the Y-chromosome signature of Robert E. Lee must be established, preferably by testing proven descendants of different sons [of Lee]. Then your mother must locate a male cousin who still carries the surname Lee, to see if the DNA signature matches.

My grandmother was adopted, and I’ve recently connected with a woman whom I believe could be my biological first cousin. How could DNA testing help us learn whether we’re cousins? I’ve heard that female DNA testing only tells you about your ancient ancestry.

TURNER: There are other types of DNA tests for this situation. Paternity testing laboratories can assess more distant relationships than the customary father-mother-child triad. First-cousin relationships are about the limit, though.

WOODWARD: Relationship testing requires testing of the two people living today using autosomal markers. [This type of testing] can determine if a person is a sibling, cousin or not related. It’s always better if you can test multiple people in the family. It adds strength to the result.

I think my paternal grandfather’s family came from Ireland or Germany. Which DNA test should I take to find out the right country?

TURNER: This is pushing the limits of DNA testing. Some Y-DNA signatures may be more common in Ireland than in Germany, or vice versa, but Europeans have been moving around the continent for thousands of years, so any signature can show up in multiple locations. But if you can [genetically] link yourself to a specific family whose members know where their ancestor resided, that can provide a clue. For example, a fellow with the surname of Lawrence learned that he matched a Lorentz family, so he shifted his research from England to Germany.

WOODWARD: Look for a paternal descendant to test the Y-chromosome. Go back and put that result in the Sorenson database, [which contains more than 60,000 DNA samples linked to family trees from men and women around the world,] and pull up all the individuals who share that haplotype. Then look to see which “supergroup” that haplotype belongs to. A supergroup tells you a deep origin; for example, whether it’s in Europe. Your best bet is to compare your haplotype with the Sorenson database, and then compare [the resulting matches] to genealogy that goes back to the 1800s and earlier.

I want to learn where in Africa my ancestors came from. What DNA test should I take?

PAIGE: Many African-Americans hit a brick wall in the late 1800s. Black people weren’t recorded by name until the late 1800s. DNA testing can help people identify where their family was prior to the slave trade. We provide the present-day country (or countries) that has people living in it today with whom you share ancestry.

TURNER: It might require Y-DNA and/or mtDNA testing of many cousins to learn which of your many ancestors came from Africa. Your own mtDNA follows your mother’s mother’s mother’s (and so on) line. If you think your African ancestry comes from your father’s father’s mother, you’d need to find a straight female-line descendant from her — in other words, a cousin.

DNA test results can almost always tell if the origin is the African continent, but they can’t always get down to the tribal level. [Companies such as] African Ancestry check if you have matches with samples collected from different tribes, but that doesn’t necessarily mean your ancestor came from that tribe. You might have a sixth-great-grandmother whose descendants went to live in different tribes.

I want to find out which side of my family came from Africa. What test should I take?

PAIGE: If you are specifically looking for an African result, take the maternal [mtDNA] test. Over 90 percent of those lines for African-Americans come back African. For single paternal lineages, 35 percent of the time results come back European. That doesn’t mean [the test subject] isn’t African … It was mostly white men fathering children with African women.

MY mtDNA test shows I have Asian blood. How can I determine which ancestor was Asian?

CHARLTON: There’s no way to tell which specific ancestor was Asian from any of the DNA tests — mitochondrial, Y-chromosome or genomic. [This is due to] the random recombination of the DNA markers at each mating for all those ancestors. This would be true for all ethnicities. The human genome is 99.9 percent identical among all humans. All the differences in humanity lie in that 0.1 percent, and of that, we can only evaluate the tiniest fraction.

WOODWARD: mtDNA is inherited from the mother. If a person has an mtDNA test that suggests they have Asian DNA, this tells that the maternal line has it. But it can’t tell you which of your ancestors actually lived in Asia.

HOW do I decide how many markers I need to have tested?

WOODWARD: Always get the maximum number of markers tested you can afford, up to about 40. The more markers, generally the more accurate the test will be. As the technology continues to improve, additional tests with more and different types of markers will become available.

My DNA test results are confusing, with all the charts and lines and admixtures. How can I make heads or tails of this report?

CHARLTON: In the Ancestry Genomics tests, just check the bar graphs that show the Most Likely Estimate of ancestry as blue bars (showing results with 95 percent or higher confidence). The red lines within the blue bars are the ranges of possibility (showing results with confidence range between 85 and 95 percent). In the Y-DNA and mtDNA tests, you have to look at how the haplogroups link to similar haplogroups found from the databases in regions around the world.

PAIGE: One of the things we have on the AfricanAncestry.com site is a science center, an interactive tool that helps you understand your test results.

WOODWARD: We’re working on ways to give the answers and not the confusing stuff. Sorenson is partnering with GeneTree <www.genetree.com>, a family networking Web site, to help users interpret the data in the Sorenson database more easily.

What do the companies do with my DNA after the test?

TURNER: Some will store the DNA for a set number of years, so that additional tests can be performed without submitting a new sample. Others discard the DNA after a few months. Ask your testing lab about its policies.

From the March 2008 Family Tree Magazine

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