DNA and the GPS

DNA and the GPS

Alphabet soup

It’s a question that leaves The Legal Genealogist utterly baffled.

Yet we hear it all the time.

DNA.standardsFrom individuals looking at what they see as brick walls in their own genealogy.

From researchers looking at family history mysteries.

Even from students excitedly leaving the first-ever week-long institute-level courses in DNA.

“Can it be,” the question goes, that “DNA is part of the Genealogical Proof Standard’s first element: the requirement of a reasonably exhaustive search?”

Everybody agrees — or at least seems to agree — that DNA is mainstream now. That it’s a cool tool for resolving issues of proof and relationship that can’t be solved in any other way.

It’s so very much a part of our genealogical thinking now that an entire room full of genealogists watching the Cynthia Nixon episode of Who Do You Think You Are? in the common room of the Genealogical Research Institute of Pittsburgh 10 days ago all spoke up when Nixon wondered who the father of the baby born in prison might have been: “Do some DNA testing!”1

But they just aren’t quite sure — aren’t quite ready to say — that it should be part of a research plan to conduct a reasonably exhaustive search. That it’s part of the GPS.

Um… why wouldn’t it be?

Let’s start by making sure we all understand just what the GPS — the Genealogical Proof Standard — genealogy’s best practices that we all aspire to follow — means by a reasonably exhaustive search.

That GPS element calls for a reasonable effort to identify and examine “a wide range of high quality sources” in order to minimize “the probability that undiscovered evidence will overturn a too-hasty conclusion.”2

We want our research to be thorough, and that means we try to “gather all reliable information potentially relevant to the research question, including evidence items conflicting or consistent with other evidence items. Thorough research, therefore, aims to consult all potentially relevant sources. It emphasizes original records containing primary information, which may be used as direct, indirect, or negative evidence.”3

But there’s a reason why the standard is called a reasonably exhaustive search, not just an exhaustive search. The simple fact is that there is “a nearly infinite number of genealogical sources” and looking at them all is, to put it mildly, “impractical. … Convenience, expertise, financing, location, or practical concerns may limit (a research) plan’s scope.”4

So… is DNA testing the kind of “high quality source” that could keep us from making a “too-hasty conclusion”? You betcha. And that’s why we need to consider it, each and every time we are putting together a research plan to try to solve a genealogical question.

But it doesn’t mean we can use it in every single case.

First and foremost, there are some occasions when DNA just isn’t going to give us the answer we need.

Say I want to know for sure if I descend from the William Pettypool who lived in St. Mary’s County, Maryland, in the late 1600s. I can’t get the answer from YDNA testing because that sort of DNA only passes down the male line.5 Not only am I a female but I descend from a Pettypool female many generations ago, so I can’t even ask brothers or close cousins to test.

I can’t get the answer from mitochondrial DNA because that gives me my mother’s mother’s mother’s info6… so even if I had a direct unbroken female Pettypool line, it will never connect me directly to William himself.

And autosomal DNA generally can’t give you a reliable answer to a relationship question back more than five or six generations7 — and William would be my 9th great grandfather. That’s way too far back to be answered reliably with autosomal DNA.

The GPS with its reasonably exhaustive search element doesn’t require me to do something that isn’t likely to produce a reliable answer.

Second, even if I could positively identify a male cousin somewhere in my Pettypool line and a male descendant of William who might be able to answer the question with YDNA testing, one or both of those men might not be willing to test. We’ve all encountered cases where the one person we really really need to agree to DNA testing to get a question answered is the one person who is convinced that DNA testing is a communist plot.

The GPS with its reasonably exhaustive search element doesn’t require me to violate the law or ethics and steal DNA samples a cousin or test candidate isn’t willing to give.

And, of course, even if everybody involved is perfectly willing to do all kinds of DNA testing, the results often won’t give us a definitive answer anyway. Even if my documented male Pettypool cousin matched a documented descendant of William, it wouldn’t tell me that I descend from William: my line could be from a brother or cousin or uncle of William. DNA only works with the paper trail research, not instead of it.

The bottom line here is straightforward: DNA is exactly like every other kind of evidence we use in genealogical research.

Every time we consider a research question, we think about what we might look at to answer it. If I want to nail my ancestor’s feet to the floor in a particular place and time, I’d look at deeds and probate records and tax records and court records. The kinds of things that will document his or her presence when and where I think he or she was — or should have been.

But for that kind of research question, DNA testing probably isn’t going to be in my research plan. It’s not the kind of high quality source that’s likely to give me the answer I need for that particular issue.

On the other hand, if I want to know if two Smith lines in Rowan County, North Carolina, are related, then of course I’d consider DNA testing, and try to find male candidates from both lines who were willing to test.

In other words, if DNA testing is available and it’s going to contribute to a reliable answer to our research question, then why wouldn’t we do it as part of our reasonable exhaustive search?

And if it isn’t available or it won’t help answer the question, then … sigh … we’re back to plowing through all the other types of evidence we might find that will.


  1. It really was odd that they didn’t use it in that episode, wasn’t it? Can’t help but wonder if the baby Sarah left no descendants, or the descendants weren’t willing to test, or…?
  2. Board for Certification of Genealogists, “The Genealogical Proof Standard” (http://www.bcgcertification.org/resources/standard.html : accessed 2 August 2014)
  3. Board for Certification of Genealogists, Genealogy Standards, 50th Anniversary ed. (Nashville, Tenn. : Ancestry, 2014), 14, Standard 17.
  4. Thomas W. Jones, “When Enough is Enough: How Much Searching is ‘Reasonably Exhaustive?’” Association of Professional Genealogists Quarterly 25 (March 2010): 25-33.
  5. ISOGG Wiki (http://www.isogg.org/wiki), “Y chromosome DNA tests,” rev. 5 March 2014.
  6. ISOGG Wiki (http://www.isogg.org/wiki), “Mitochondrial DNA tests,” rev. 9 July 2014.
  7. See generally Judy G. Russell, “Autosomal DNA testing,” National Genealogical Society Magazine, October-December 2011, 38-43.
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26 Responses to DNA and the GPS

  1. About 1: I think many excellent sources don’t make it into the WDYTYA episodes. They pick the sources that allow them to best tell the story to a wide audience. Going into DNA would probably take some explaining and would use up time that they needed to tell the story of the imprisonment. I loved the final result and understand why the editors would choose to do it this way.

    • CeCe Moore says:

      Yvette is absolutely correct. Much of the research doesn’t make it into the show. I’m sure when Finding Your Roots airs, many will be asking the same question when in fact we DID use DNA, but it just didn’t make it through editing.

    • Judy G. Russell says:

      I understand that only a fraction of what gets researched can be included, but the whole notion of who Sarah’s father was seemed to underlie the episode. We ended up knowing she wasn’t Noah’s, we ended up hearing Cynthia Nixon repeatedly wonder about it, we all (I suspect) ended up thinking long and hard about the warden — and the conduct of the warden’s wife towards the baby — and DNA could have answered that.

      • Jason Lee says:

        It surely seemed like a missed opportunity to highlight the power of DNA testing by at least mentioning the possibility.

      • Concetta says:

        It makes me wish there was a follow up web series. I understand why they did the story the way they did, but for the genealogy fans in the audience, I wish they could have gone into more detail. I know I’d kick Ancestry a couple bucks an episode to see topics like DNA covered with the star in more detail.

  2. Nathan W. Murphy says:

    In my work for Price and Associates Genealogical Services in Salt Lake City, we’ve been using DNA testing to help clients for more than seven years. The fact of the matter is, the client could pay $150-300 to buy a YDNA kit or two upfront, or spend $5000 for research on a brickwall. YDNA has helped many of our clients resolve brickwalls much less expensively, more quickly, and more concretely. P&A researchers usually combine the two approaches though (documentary research and genetic research), rather than select one technique or the other, i.e. Chris Paton’s “dual approach.” Having a client submit a DNA test upfront can often significantly reduce the amount of documentary research that needs to be done to make a strong case, lowering the client’s overall bill. I like to compare it to giving the doctor an X-ray before he treats you. It opens up many new research possibilities that historical records alone may not have suggested.

    When applying for professional certifications in genealogy today, I would be in favor of penalizing applicants if DNA could have helped solve a problem that they leave unresolved, and they don’t recommend it.

    • Judy G. Russell says:

      If DNA testing is available and relevant (it sometimes isn’t), then doing both is, in my judgment, the ONLY thing that makes sense, since without the paper trail the DNA evidence is rarely if ever adequate for ANY genealogical question.

      • Jason Lee says:

        I think that just about everyone who can afford to hire a professional genealogist (and cares enough about their ancestry to do so) should be strongly encouraged to cough up $100 for autosomal testing if they haven’t already done so.

        It’s a cheap way to find a lot of information. NPEs happen. Surprises lurk. Unasked questions can be answered. If you haven’t tested your DNA, you’re walking around with a gold mine. Dig in!

    • Jason Lee says:

      I like the medical analogy. I think that in the near future, professional genealogists who aren’t proficient in using the tools of genetic genealogy should be treated like a doctor who can’t understand a medical chart.

      Likewise, in the not-so-distant future, I think that family trees that include no DNA information should seen as being as unreliable as a tree that arbitrarily excludes census information.

      • Judy G. Russell says:

        I disagree strongly, because family is more than bloodline.

        • Jason Lee says:

          Thank you for the reply.

          As many adoptees (and children of adoptees) can attest, it is nice to have a family tree that accurately reflects bloodlines. I know many non-adoptees feel the same way.

          My main point was that as ubiquitous as DNA is becoming, and as powerful as it is and as accuate as it is, all genealogists should be using it as much as possible.

          As you pointed out in your post, we’re well past the point at which DNA should continue to be treated like the proverbial red headed stepchild of genealogy.

          That’s why I say that some point in the future, it should be as startling to find a well-documented tree that completely excludes DNA research as it would be to find one that is conspicuously devoid birth records or death certificates.

          If DNA results keep piling up and we can’t bring ourselves to say that DNA evidence should become a ubiquitous component of well-documented family trees, maybe GPS is correct to refrain from saying that DNA should be part of a research plan to conduct a reasonably exhaustive search.

          • Judy G. Russell says:

            I am emphasizing that family is more than just bloodlines, Jason. A truly excellent family tree might be recording the social history of a person in a family, not merely his or her biological relationship to others. Both biology and love can form families — and, of the two, love is more important.

  3. Makes perfect sense to me. It’s just that in most of the cases we encounter it wouldn’t be required: for the reasons you mentioned and because not enough other people have been tested with whom we’d want to compare. I have a current client in that boat. That doesn’t mean we shouldn’t advise people to get tested or have relatives tested, in the eventuality that their descendants might want their DNA stats.

    But now you’re making me realize that I should address the question with every client, in every report, every proof argument. Either lay the thought to rest for them, or propose it.

    Exciting times!

    • Nathan W. Murphy says:

      In the situation where the client needs more people to compare against, we explain to them that they should proactively encourage more people we think they are related to to be tested by financing tests for the possible cousins.

      • Judy G. Russell says:

        And if the people say no, and if the people can’t be found or — as in many cases — simply don’t exist in small families that may have daughtered out generations ago — you can be willing to pay for all the tests in the world and still NOT be able to use DNA.

        • Jason Lee says:

          Likewise with other queries. You can be willing to invest large amounts of time and money looking for and poring over deeds and probate records and tax records and court records and still NOT be able to use any of it to nail down the answer your question.

          But you’re certainly not going to find anything under the stone that remains unturned.

          A distinctive feature of DNA testing is that even when if you start with a very specific question and fail to find the answer, consolation comes in the form of unanticipated revelations and answers to other questions. (Not to mention the benefits of creating connections with hundreds of cousins, many of whom might have precious information and resources that you would not have found otherwise.)

          For some, there’s certainly a risk of disappointment stemming from misinformation and unrealistic expectations about what a DNA test can or cannot do, but I’d be willing to bet real money that there are more people who are missing out on the benefits of DNA testing because they don’t know how to use it and don’t understand the potential (or believe that it is wholly unreliable).

    • Judy G. Russell says:

      It is exciting indeed, Polly, and I think your approach is a good one: address it in every case, with why it can — or can’t — work for this issue.

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  5. Sharon E says:

    OK, Judy,

    I’m dying to know what you know about “two Smith lines in Rowan County, North Carolina”, as I descend from Samuel Smith and Hannah Jane Kiteley. Is there a possibility that you also descend from a Rowan Co. Smith family?


  6. Jason Lee says:

    “And autosomal DNA generally can’t give you a reliable answer to a relationship question back more than five or six generations…”

    I understand the point here in the broader context, and I appreciate the qualifier — “generally” — but there are too many otherwise well-informed genealogists who think that DNA is pretty unreliable, period. (Maybe they WANT to think it’s unreliable because they haven’t yet taken the time to learn how to use it.)

    I would go so far as to say that DNA is more reliable than anything else you’ll ever use in genealogy. I’ll go even futher: DNA is always reliable, period.

    Don’t blame DNA if you don’t have enough DNA to prove what you want to prove. And don’t blame DNA if you can’t find a volunteer who has the DNA you need. Of course it’s absolutely true that DNA cannot answer every question, and sometimes people misuse DNA to jump to wrong conclusions, but those are not questions of DNA’s reliability.

    It’s also absolutely true that going back more and more generations, a smaller fraction of one’s ancestors will be represented in one’s genome. Six genrations is indeed a point at which some ancestors can be expected to drop off your “genetic family tree.” But if, for example, three or four people all mutually share 25 cM of DNA on the same chromosome in the same location, they can know with great certainty that they share common ancestry — and that’s no less true if they have to go back more than six generations to find the shared ancestry. DNA is reliable.

    I know that people who have immersed themselves in genetic genealogy understand all if this very well, but there are many informed genealogists who clearly do not. So I am loath to use “unreliable” and “DNA” in the same sentence, for fear of reinforcing misapprehensions about the reliability of DNA.

    • Judy G. Russell says:

      I understand your point, Jason, but when it comes to autosomal DNA, we are dealing with a fundamentally different descendancy system than with YDNA or mtDNA. With mtDNA or YDNA, you are not going to find a third cousin in your direct line who doesn’t match. But that happens in at least 10% of autosomal cases: the two cousins just didn’t happen to inherit enough of the same segments from the same people to show up as a match. So while a negative result in YDNA or mtDNA testing is reliable as an indicator of a lack of relationship, that’s not true of autosomal DNA.

      • Jason Lee says:

        Thanks again for your post and your follow-up comments.

        Certainly each DNA test has its own role, as your readers well know. With autosomal testing, you can learn about every line, but as you have emphasized, you won’t catch every relative, even within the 5-6 generation window. mtDNA testing is very limited niche. YDNA is a very useful test, but it only reveals a sliver. It doesn’t provide information about your paternal grandmother’s relatives, as so many seem to believe. And if the paper trail leads to a chasm, YDNA might do absolutely nothing to facilitate observable progress.

        Anyone who has an interest in genetic genealogy should study the quirks of each test assiduously, and I sincerely hope that anyone who has an interest in autosomal DNA testing will go into it knowing the benefits and limitations.

        What frustrates me is when I find people who have been oversold on the limitations DNA testing. E.g., the family member who stubbornly insists that women cannot do DNA testing.

        Here’s another example I recently found on a message board:

        “My wife did a dna test to find her ancestry. She is 50% French and report never listed any French ancestry. It looks like a scam . Has anyone else used this.”

        Here’s one of the answers:

        “Personally I don’t believe the DNA tests work for testing ancestry.”

        Here’s another:

        “DNA is not an exact science. We are led to believe it is, but it is not. It is still someone’s opinion whether all those strands actually match, or not.”


        “I think it’s legit, but you can get all the same information yourself without paying them. Also, they make a big deal about checking your DNA and finding familial matches, but that really doesn’t do anything for you.”

        Here’s something that a DAR genealogist with decades of experience told me personally:

        “DNA is really too primitive and very inaccurate as we can see by our connections.”

        This hurts me deep down inside my soul!

        I know people need to understand that DNA testing is not magic like an episode of CSI. But it pains me to see so many people holding a misinformed opinion at the other extreme.

        • Judy G. Russell says:

          To some extent, the DNA testing companies bring this on themselves (and on us as genetic genealogists). The problem is their advertising focus on the ethnicity estimates — which frankly do deserve the criticism and skepticism we see. For the most part, they’re no better than what engineers called WAGs (wild-ass guesses).

          • Jason Lee says:

            Good point. Too few in the business of selling tests understand the potential (and limitations) of genetic genealogy. Even fewer (count ‘em on one hand?) have a strong understanding of the nuts and bolts process of doing genetic genealogy.

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