DNA/mtDNA Made Easy

d The following article appears in the December issue of the Lanarkshire Family History Society’s journal based in Glasgow Scotland. Jim Leonard is the president of the society producing the journal. He contacted Team Liddell in October in response to our posing our DNA/mtDNA Study’s launch date since his grandmother was a Liddell and asked about becoming a participant. He so enjoyed our detailed reply setting out why he would not be a prospect that he invited us to submit a article for his group’s journal. The offer was accepted and then expended into a two-part series when it became apparent that there was a value for males to also test for their mother’s mtDNA, especially when they are the only living person left of the family and there are no female survivors. This new facet to genetic testing was the subject of the second article. c

A New Tool for Family Genealogists: Genetic Testing

By James Wallace Liddell

A rapidly emerging new tool for genealogists is the Y-DNA/mtDNA study, and it really isn't too difficult for even the science-challenged individual to understand and use successfully.

This is true only if genealogists don't delve too deeply into the scientific underpinnings of their remarkable new tool, for the language of genetics rapidly becomes a dense science language at its lower levels. In short, stay high in order to fly!

It takes an understanding of only three elements to set up an effective Y-DNA/mtDNA study and these are easily mastered--a family's surname history and variant relationships, basic reproduction biology, and cousins-pairing/testing. The companies that perform the tests provide fulsome explanations of the test outcomes--so, don't worry about those number-filled charts. Everything is explained in understandable detail by the end of the process.

A good study always begins with a thorough understanding of the family's surname, its history and likely variant spellings.

The surname is what a husband brings to a marriage along with his male Y-DNA chromosome, which is embedded in his 'general' DNA package, just as the wife brings her female mtDNA, which is embedded, in her general DNA package. It is the merging of these two DNA packages, which, of course, produces a baby--a boy baby, if the male surname-specific Y-DNA dominates at the moment of conception, and a girl baby if it doesn't.

The genealogical implications and how the biology works at the chromosomal level are best illustrated in a reply by Team Liddell et al to one of its members following its announcement that it was launching its Y-DNA/mtDNA study on October 15. The member--let's say her name is Mary (nee Liddell) Selkirk--it isn't, actually--wrote one of the Team's volunteers before the launch date to ask if her Selkirk son could take part in the group's study.

The Team volunteer’s reply--modified for this article--began:

"Dear Mary: Your son could take part in our study but it would be a waste of time. Your son carries your husband's Selkirk Y-DNA and that isn't Liddell Y-DNA. Our study is interested only in Liddell Y-DNA and the Y-DNA of the surnames we surmise, like our own, to be derived from the ancient Scot border region's place-name, Liddesdale--such surnames as Liddle, Lidell, Lydell and so forth for a total of nearly 90.

"A male's Y-DNA comes to a traditional marriage along with his surname. These marital surnames are what the Team uses to sort out and identify prospects for likely kinships among the various surnames we are interested in, based on our previous records research.

“Yes, your son received a blend of general DNA from you and your husband, but this non-Y-DNA and non-mtDNA isn't genealogically interesting. Only the Y-DNA and mtDNA is interesting. But this is where nature gets a little tricky, Mary, and you need to know the rest of this story.

"You contributed your Liddell mtDNA to your son--mtDNA is the short name for the female's gender-specific chromosome, mitochondria is the long name--and you passed this on to him, but it will die with him. He cannot pass it on to his daughters. Instead, they will get their mtDNA from their mother, his wife.

"Your Liddell mtDNA passes on to future generations only through your daughters and you didn't have any according to the chart you provided the Team. Of course, your (nee) Liddell sisters will pass to their daughters mtDNA, which is identical to your own in a process which will last for countless generations into the future even though their surnames will change in traditional families with each generation.

"But this mtDNA of yours also goes back very likely completely unchanged for 5,000, even 10,000 years. All mtDNA has an archaeological nature, you see, and not a genealogical one. This is so because a female's mtDNA very rarely 'mutates' as the scientists call the process.

"On the other hand, male Y-DNA mutates comparatively rapidly.

"By mutation, we mean that, at conception one of the 45 or so markers on the Y-DNA chromosome--if a baby boy is the end result, or one of a similar number on the mtDNA chromosome if a baby girl is the end result--has a very slight chance to shift one position up or down on its chromosomal ladder. A very slight chance, indeed, for Y-DNA has only a 0.002 percent chance of mutating one position every generation, which figures out to be an expected mutation every 330 or so years.

"With females, the odds figure out to be an expected one-position mutation every 5,000- to 10,000 years. In either case, the effect is totally invisible to the eye, Mary, for we are not talking here about suddenly seeing seven fingers or plump little tails on babies. No, we are referring to minute changes visible only under an electron microscope.

"As you undoubtedly realized just now, there's quite a difference between a position shift every 330 years and one every 5,000 years, and it's this much more rapid beating of the male Y-DNA bio-clock that is exciting today's genealogists. Ever since 2000 when the rate of Y-DNA mutation was figured out at the Max Planck Institute in Berlin, we can know with high certainty the various types of kinships among individuals bearing the same or similar surnames when matches or near-matches are found in their test results.

"Sometimes--now--we can even identify with reasonable accuracy the century when two male lines split from each other--and we can get very good indications for this even 600 years ago, perhaps even 27 generations ago--and those periods certainly fall deeply into Scotland's ever-increasing scarcity of records for most Scots prior to the 1500s.

"Do you understand now why our Team has worked so long and hard on setting up our study? We--Liddell, Lidell, Liddle, Liddil, all 90 surnames, all of us--are hitting the no-remaining-linkable-records brick wall of the 1600s and 1500s, and now we must turn to this new tool to keep reaching back along our lines if we are to reconstruct our now-worldwide family.

"Won't it be wonderful to know that the Y-DNA of an Australian Liddell is linkable to a Canadian Liddle and they to a Northern Ireland Lydell? And that some Lindell-kindred lady in New Orleans has an mtDNA Bertini sister in Rome?

"Yes, we also have an mtDNA study for our female members, but it is going to take a woman with a very wide genealogy chart and a lot of determination to make her test investment profitable. She will have to pursue her mtDNA-sisters across a huge numbers of different surnames to find them. It can be done and we will help as best we can--but, admittedly, Y-DNA testing is a much easier task."

The letter to Mary (nee Liddell) Selkirk goes on to explain that a properly surnamed male's DNA test results can turn out a no-match with all other males in the study because of an unknown adoption or infidelity occurring sometime in his line. One authority states that this is very rare--perhaps on the scale of a 0.02 percent chance per generation.

There is one other remote possibility, that two males can match on all markers and still be unrelated. If nonsensical matches appear, just remember that nature can sometimes have a perverse nature, and non-kin matches can happen. This is rare, though, and these outcomes can be safely ignored.

--Just remember, always keep an eye on thee surname list and a study should go smoothly and there will be few if any operational surprises. Team Liddell et al, for example, first assembled all likely surnames--nearly 90 in all--before doing anything else, and now knows how to look not only for the most common similar surnames but also rarely encountered spellings such as Leedahl, Leidel, Lide, Lindel and Lytel.

The general goal for a study is to establish solid Y-DNA matches within lines with the longest reliable documentation and also for each small family interested in linking to these lines, or to each other.

The president of a company reputed to be handling some 90 percent of the current genealogy-related genetics testing recently wrote the Team to suggest that it is best to test a pair of male third-cousins or ones farther apart, and that pairing sixth-cousins would be a very good span, indeed, across a family.

In any case, it is not profitable to test two or more males from a father-son-uncles-brothers cluster since all are assumed to have the same Y-DNA, and nothing is gained thereby. One male will be sufficient to test all in the cluster, for the chance of one member of the cluster having a mutated Y-DNA chromosome is tiny for any given generation, and generally can be safely disregarded.

Testing within the third- to sixth-cousin range, therefore, should be the standard to strive for when setting up a study. Being an organization, Team Liddell et al believes it can take the long view, and suggests to its members and those joining its study that it can sometimes be possible to establish a Y-DNA benchmark for a line or a small family by testing only one male. If even just one match with any male from any of the other lines is revealed, then a reliable benchmark for both that line or small family and the others has been established and some money has been saved by testing only one male in each group.

If no match is found at all for the single male with any of the other tested males, then only six weeks to two months of time has been lost, for that is how long it takes for a second male to self-administer the inside-cheek scraping test, mail the two small container tubes to the testing lab, receive the test results and then attempt another round of matches with the previously tested males.

If there are still no matches of one properly-surnamed group, then there may be something wrong with their genealogy research, they may have a assumed surname or there could be an unknown adoption or an infidelity in the past.

This is why a thorough knowledge of the families' surnames is so critical. Sorting out the surnames and observing their relationships in the existing records and targeting potential test-takers saves huge amounts of testing time and costs once the study is underway.

And, of course, the ultimate objective is to establish kinships among living people independently of documentation, even if the records were destroyed or lost hundreds of years ago or, perhaps, never existed.

There is one other aspect to Y-DNA and mtDNA testing which is fascinating for some and which reaches back to truly ancient times, especially for those whose ancestors lived in the vicinity of Hadrian’s and Antonino's walls. This is "deep-ancestry" test interpretation and comes from the literally personal history recorded in the first 12 markers tested by the 37-marker Y-DNA and Enhanced mtDNA tests recommended by Team Liddell et al. These markers are used to define one's most remote ancestors--perhaps a trace of some long-dead Roman legionnaire who was from the Middle East or possibly of some more recent Viking, or even a Celtic or Gaelic ancestor—or a mixture of several.

For some, this is the best part of a study. For others, it is just a nice thing to know.

The Web has a large number of related websites to explore for additional information. A few are listed below.

A Partial List of Relevant Websites

FamilyTreeDNA Testing Service (Commercial website containing tutorial and reference library) http://www.familytreedna.com

Mitochondrial DNA (Wikipedia Free Encyclopedia) http://en.wikipedia.org/wiki/Mitochondrial_DNA

DNA Analysis for Genealogy (Lambert DNA Project, Y-DNA Article) http://www.chem.northwestern.edu/~lambert/dna/analysis.htm

NHS Genetic Testing (July 2004) (Postnote: Parliamentary Office of Science & Technology http://www.parliament.uk/documents/upload/POSTpn227.pdf

Understanding Gene Testing (U.S. Health & Public Srvs. http://www.accessexcellence.org/AE/AEPC/NIH

(Edited by Jack Dalton Wardlaw, Editor-Team Liddell et al, Oct 2004)

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