"How To" Compare Y-DNA Test Results

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d Team Liddell et al    c

“No Longer Separated by Oceans and Centuries”

The "How To" File on

Comparing Y-DNA Test Results

 (First issued to a portion of the Membership by Team Liddell et al on 24 June 05 and later modified slightly prior to posting here.

Note: If the indicated hyperlinks for the addresses do not function, please cut-and-paste to your browser.)


Truly, YDNA and mtDNA test results are the technological marvels of today's practice of genealogy. Both of these gender-specific tests allow you to get past the absence of records and documentation for whatever reason that they no longer exist in your searches for your ancestors. The YDNA (male) test result is particularly useful for getting the truly related back together again, even after centuries.

 BUT, there are a number of things that must be place before this tool can be successfully used. This file is intended to provide direction and guidance for the Team Member who has ALREADY read through the basic files the Team has put in place at www.Geocities.com/TeamLiddellDNA--our Study's growingly-popular, PUBLIC website which was created for your use and the use of those in whom you have a genealogical interest. This site is your authorative reference in all genetic matters involving the Team and its various projects and Studies. Likewise, you have a ready-to-hand extensive genetics reference library of a higher nature and quality at www.FamilyTreeDNA.com. Just look for the button on their opening page.

 Before getting into the Matching Gaem, please familiarize yourself with the basics of genetics by reading through our website's essays and both our male (YDNA) and female (mtDNA) interpretations that are posted at that site and also posted in the folders of our PRIVATE Liddesdale site. The Liddesdale site address is NOT listed here for privacy and security reasons. If you are a member of Team Liddell et al and don't know our various Liddesdale sites' addresses, please write to TeamLiddell@Yahoo.com and the addresses will be issued to you.

 Please follow this "How to" instruction sheet to the letter, and remember this: The Team is always ready to assist you in your genetic affairs, particularly when you are involved with our test result interpretations, or when working with someone you think may want to join our Study. Study participation is NOT reserved to Team members along--it is entirely open to the public.


 1. Your line's YDNA test results cannot be viewed as representative of your family's YDNA until there are at least two known-to-be-related males who have tested and matched at or within three mutation steps of each other and preferably with follow-up "refinement" tests as needed on their 1-12 marker array. When this condition(s) has/have been met, your line is said to have been "benchmarked" and is an extremely reliable yardstick to use in comparing to other lines, regardless of surname. When a second male, who is documentably certain to be related, has not yet obtained from within the family --preferably third-cousin status or greater--with the first male to be tested, comparisons with "matching" strangers is still possible and worhwhile, but the results of the comparison and analysis will always be suspect until your line has been benchmarked. These conditions also hold true for the non-Team line.

 2. The Team does not recognize or even discuss test results from any testing service other than http://www.FamilyTreeDNA.com (FTDNA) unless at least one of the following conditions is unconditionally met:

              A.  The Y-DNA marker array used in the non-FTDNA (alien) testing process is identical to that of FTDNA. (The FTDNA male marker array is listed in the "Interpreting Your Test Results" file provided at our Study site.  SPECIAL NOTE: Female mtDNA test-result matchings need to be handled directly from the outset by having a Team advisor work in conjunction with you. This essay, therefore, is limited to YDNA considerations since the entire genetic setup for the female "X" chromosome is too complicated to summarily treat in this brief file.)

            B. The "alien" (non-FTDNA) test result has undergone a FTDNA conciliation/conversion process to bring it in line with the standard test results that FTDNA provides its own clientele and you or the Team can verify that this process has been performed by FTDNA (Addresses are available under "Contacts" at: www.FamilyTreeDNA.com).

            C. The test results were not produced by Ancestry.com, which no longer offers a genealogy-genetics testing service and by which, while it was offering this service, an unknown number of test results reportedly were misaddressed to some of its clients. Anyone with an Ancestry.com test results has be retested by FTDNA or by some other testing service that either meets condition A, or the results meet condition B before the Team will consider dealing with the individual for matching purposes.

            D. The  non-FTDNA company is clearly described and identified first to a Team advisor who will then bring a FTDNA executive into the discussion and the test result is accepted by the executive as compatible with the testing process of FTDNA.

(Please be aware that the quality of the laboratory work is just as important as insuring that both test procedures have the same YDNA marker array.)

            E. If the non-Team member has FTDNA test results, these have to have been issued on or after 19 May 03, or they are clearly identified as to have been adjusted on that date to compensate for a universal test results change applied then by FTDNA because of a then-new lab discovery about the rate of mutation for the DYS464 a-d (and e) markers.

3. The bulk of the initial and fact-gathering correspondence with the person outside the Team will be handled by the Team member involved in the matching process, with the Team assisting as necessary in the background unless mtDNA is involved. Under no circumstances at any time in this process are Team members to be identified to outsiders except for James Wallace (Jim) Liddell, who is available at TeamLiddell@Yahoo.com.

4. It is essential that you never refer to a Study participant by anything other than the kit number that person was assigned by FTDNA unless you have that person's written permission and the Team has been provided a copy of this at teamliddell@yahoo.com.  The reason for this iron-clad rule is the Team goes to exceptional extremes to protect the identity of its Study's participants as well as those of its general membership and has repeatedly assured all Study participants that their identities are secure and will never be revealed to anyone without their written permission. This is also the firm policy of FTDNA and the Team uses that company's policy as its own in this matter.

5. Contact with FTDNA executives must be kept to a minimum and it is always best to first try working with the Team before contacting FTDNA if you have encountered an extreme unusual situation and FTDNA test results are involved. --Still, please remember that FTDNA executives are always available to their company's clients, individually and directly.

6. Be confident about your test results AND your Team Liddell et al data interpretation. Every interpretation issued by the Team is based on those issued by FTDNA but rewritten by a knowledgeable member of Team Liddell et al and only slightly and conservatively expanded and extended through the use of academically-solid histories and materials from other disciplines, has been vetted by an outside advisor-expert in genealogy genetics, and then rewritten before being publically released. That means that your data is as good as it can get in genealogy genetics. Rely on the Team's interpretations for accuracy and completeness at all times and under all conditions.

7. Never fall into the trap of "comparison-directional displacement." In other words, never allow yourself to wonder why your test results are similar to those of another line but rather, wonder why theirs are similar to yours. Because of the care extended by the Team during the interpretation process, your data is the yardstick to measure by and not the other person's.




 1. Start by working with identical or very similar surnames for closely-testing males--or begin by questioning why the surnames are drastically different. If dealing with the latter case, spend a lot of time on Step Two in this list before proceeding further. Another facet of Step 1 is to compare haplogroups. ("Genetic Tribe" is a reasonable definition of "haplogroup".) The haplogroups for the lines under review HAVE to be the same regardless of surnames or apparent test results similarities. If the haplogroups are different, then any apparent kinship is impossible.

 2. Ensure that the other person has solid documentation for their genealogy charts and the surname(s) under discussion. and--when more than one surname is involved--determine when the variation first appeared in that family and obtain documentation for this appearance--or at least get a reliable estimation of the time period for the appearance of the variant surname. (NOTE: Records from LDS archives are not longer accepted by the Team except for general guidance in research, and now are never regarded as authoritative. If more than one generation in the other person's genealogy chart is LDS-sourced and this is all the other person has, then first describe the situation to the Team and get advice before proceeding. This will rarely become a "drop-dead" situation for the Team member, but if more than one generation is LDS-based, comparison and matching efforts must always be regarded as mid-range-or-higher suspicious in nature, regardless of the final outcome.)

3. If more than one surname (similar or otherwise) is an acceptably-close part of the non-member's YDNA testing cluster, the various surnames must be explained satisfactorily and with documentation for each surname's appearance in the records, and, when possible, the reason(s) why it or they is/are different and the time range when it or they first appeared in the records.

4. At a minimum, thoroughly spot-check the documenation provided to you against original records whenever possible. Never rely exclusively on the other person's ability to perform accurate genealogical research. Always test-drive the product before "buying" it.

5. Check to make sure that the genetic test results being reported to you as theirs meets the conditions set forth in Essentials 2, A-E, above. If these conditions are met, then make sure that the DYS markers in their charts and your own are identical and in the proper sequence and that all entries are correct. If possible, obtain a copy of the non-Team-member's testing service's original test-report file and compare this to the other person's entries in the other person's publically-displayed chart if that is what you have been relying on up to this point..

6. Provide these materials to TeamLiddell@yahoo.com and ask for an analysis of the data that you have gathered under Essential Steps 1-5, and for advice on how to proceed. (In reporting YDNA chart entries, an ordinary word-processor file is acceptable if the in- and out-Team test results are set out side-by-side in parallel rows, either vertically or horizontally, and then carefully proofread.

7. At this point, a Team advisor will begin working as closely with you as is necessary to complete the matching process you are involved in.


1. At the most basic level whenever data defy logic, records cannot be used to explain to explain YDNA. Instead--in these situations, YDNA must be used to explain the records or else, to require their complete dismissal from further consideration. Sometimes, but only rarely, there are some mysteries that can never  be solved with present data.

2. Never question the accuracy of your FTDNA test results. The company's reports are as good as it ever gets in genealogy genetics. When difficulties are encountered during matching efforts, look for your explanations elsewhere.

3. Only very rarely--so rarely that you will probably never experience it in your entire life--do false perfect or near-perfect matches occur. Nature, however, can be perverse and false matches do occur--and usually as a product of random convergence of mutational processes, but not often at all.

4. Infidelities and unknown adoptions are rare. Scientists estimate that these two, plus hospital-nursery "swaps," which are even more rare events, probably amount to less than 2.5 percent of all births per generation in any culture. If a small group of males with the same surname and apparently close and documented relationships do not match genetically with the rest of their apparently close and documented male relatives, then one or more of the factors listed here HAS to be present in one of the two lines' past history and more likely in that of the smaller group.

5. Only under exceptional conditions will Team Liddell et al consider YDNA matches involving four-mutational steps of separation between two males. So should you.

6. Except for the possibilities discussed in Tip 4 above, YDNA comes with the surname down through the generations of a family line. In other words, a Smith grandfather's YDNA cannot be present in his Jones grandson but the Jones grandfather's YDNA will be present. And, while a son inherits his mother's mtDNA, it will not pass it his daughter but will die with him and it never affects the YDNA he inherits from his father which, of course, does not pass to the son's daughters but only to the family's sons. So, if a man surnamed MacDonald has a nee-Selkirk paterial grandmother, he is a sex-chromosomal genetic alien to her. He has none of her Selkirk mtDNA at all, for all of his mtDNA came exclusively from his mother.

In a very real genetic sense regarding his genetic makeup, a son is a biological half-sister to his mother.

7. When attempting matches, also look at the regions or nations of ultimate origin provided by FTDNA for the men being compared. All other things being equal and with a three- to four-mutational variance between their genetic patterns present, then if FTDNA says one male's deepest ancestors came from Iceland or Ireland (with 15 approximate matches out of 1504 reporting those two nations as their likely place of origin during the kit purchasing sign-up process) while saying that the other male's deepest ancestors originated in Latvia (with 3 matches out of 259 reporting), then the two men are likely to not be related.

8. Returning to a theme introduced in Tip 3, please be reminded that nature can be perverse and sometimes random convergent mutational patterns can arise for two lines and becomes obviously present when the documentation is incontrovertibly solid (a very rate exception to Tip 1. Convergence always means absolutely nothing for the hopeful family genealogist looking the two close patterns and wondering what may have happened "back then". The process is rare in all cases and if more than two or more lines (surnames) are involved in the matching effort, then this possible explaination should be totally disregarded as a possible explanation for the observed patterns simply because something else has to be afoot in the situation.

9. Study the histories and meanings of the surnames involved and remember that a surname based on a formal place-name trumps all other surname-origins in the variation game. London is a perfect example of a formal place-name. Next most powerful is the place-type derived surname. Carr is a good example. It is Celtic for fort-dweller (cathair). --This is not specific as a city's name woould be, but the place-type derived surname is more powerful than a descriptive surname like Redd (the color--most likely, of some ancestor's hair or complexion), and that is more powerful than Smith (an olden-time occupation) or Strong (a physical condition expressed in Middle-English (strang) as meaning "powerful".)

Surnames also can reveal a likely national origin or an ethnic group (Examples: Russians use a "...ski"-ending, whereas Poles use "...sky.")

There are a number of reliable surname reference books in print and most public libraries have at least one. The Web also can be viewed as a good source of information even though it lacks citing authority.

10. The first 12 Y-DNA markers can do nothing but confirm or deny male (or line) kinship and provide a very good estimation of a male's most-ancient ancestry. The next 13 markers (13-25) provide very good data for estimating a Most Recent Common Ancestor but this becomes a greatly enhanced and much more powerful calculation if the full 1-37 marker array is present and has been reported (or accepted as compatible) by FTDNA. Scientists are still at work on the mutation rates for 26-37 but enough is known at present for them to be presently useful. The 1-45 marker test currently offered by some companies is not accepted into its Study by Team Liddell et al for several reasons including the present opinion of most scientists that markers 38-45 have no genealogical value.

11. Do not test males closer in kinship than third-cousin unless absolutely necessary. since the generational spread between closer-kin individuals may not be sufficient to reveal a true pattern. Do not test males not yet into physical or calendar adulthood and it is best to not test the very old. And always remember that test results can be difficult to interpret or use in matching efforts if any of the involved families has a hereditary tendency to cancer (See Tip 12).

12. If a family has a history of cancer, expect to have peculiar test results as their chromosomes often can be "damaged". Drug-abuse of any type only very rarely affects chromosomes and LSD usage, never.  The jury is still out on the effect, if any, of cancer radiation treatments on chromosomes. Always ask about this factor and, if answered positively, file this information away as a possible clue for later use.

13. Some YDNA markers mutate far faster than others (there is a jet-set crowd of 12) while all mutate at different rates form each other. There is a chart of the fast-dozen at the Team's Study website.

14. Always remember that there are a lot of glib-tongued snake-oil salesmen in genealogy and even a higher overall percentage of them now are appearing in genealogy genetics. Beware of anyone who builds a Castle in Spain on the strength of a single marker or even a set of six or seven. Only the entire 37-marker array should be considered as a reliable indicator. Some very unusual genetic indications on as few as one marker CAN be entertained in some situations IF the indication is based in academia. In short, trust FTDNA, which is conservative in its interpretations, and trust the Team, which takes the FTDNA interpretations only slightly forward by refining the FTNDA texts through the use of specific academic-histories and established data from other high-quality sources, but otherwise avoid fairy-tale tellers unless solid academic sources are cited and can be personally reviewed.

15. Finally, never trust the Web for providing you with authoritative information or data. In fact, don't even thrust some of the leading subscription genealogy companies. The Team has already found profound errors in one leading genealogy company's summaries supposedly derived from U.S. Census reports. There also are serious mistakes contained in most of this same company's Y-DNA marker-displays that are prominently displayed and cited as authoritatively accurate in the accompanying texts purporting to be reliable interpretation guidance for its subscribers.

End of File


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