Genetic Testing, what to do after 25 Markers

I was working with a project member this morning who had done 25 markers and was looking for how to make sense of the match.  Here's what I told him, information that will be helpful for everyone:

I see that you have only tested 25 markers. You have 16 exact matches at 12 markers. While you are related to all those matches, they could be relatives prior to the last 700 years, when surnames came into existence. Thus, 12 marker matches do not mean much, unless you already know for sure (through a paper trail) your relationship.

At 25 markers, you have one match at a genetic distance of 1. This, again, does not mean much. Your match, Michael X*, has tested at 67 markers. So, you probably ought to upgrade your testing to 67 markers to see if you are still just one marker off an exact match, or if the match falls apart.

Here are two additional strategies you can try. Through your documented family history, find another male Taylor from your line (as distant a cousin as you can prove is your relative) and have him test. At that point, he will either match you closely (65, 66 or 67 or 67 markers), or not. If you do not match, then the paper trail is not accurate, and one or both of you descend from a line of a different male progenitor than is indicated on your genealogy.

A second strategy is to do the Family Finder test. Here you are matching autosomal DNA, matching across all family lines. While I am excited about this DNA test, and have done it for two of my Taylor and one Robinson relative, the matching is difficult so far because the people I've matched have not responded with their genealogical information. I'm not blaming them, as the protocol for how to work with others in matching autosomal DNA is not developed and many of them may be clueless. So, the science of autosomal matching is definitive, but the cooperating with one another to discover how we are related is in its infancy.

I hope all this is helpful. Please do more y-DNA markers, at least 67. Then consider the Family Finder test.  Together with the Taylor team, we should be able to assist you with your genetic matches.

Lalia
*Complete name not give for reasons of privacy.
Note: the image is a Taylor important in the history of Louisville, Kentucky, whose name I did not get.

A Model Letter to Promote the Taylor Project

Hi Fellow Taylors!



Whenever I run into a new Taylor in my life, I tell them about the Taylor project. It's hard to explain in a simple soundbite, and sometimes I'm less than successful. So I met yet another Taylor Tuesday evening, and got his e-mail and sent him this letter. It is adapted from the letter we are now sending to anyone who contacts the project, without yet being a member. I recommend you take it and modify it to your needs. I'm wondering, myself, if it would be too OCD to carry copies in my purse to hand out...



See letter below.



Lalia

~~~~~~~~~

Dear...



Here is information about the Taylor DNA project, hosted by FTDNA (Family Tree DNA). It allows you and the rest of us find our ancestral lines. Our Taylor Family Genes project posts the DNA results and family trees for members of the project. The public is welcome to view our public page, http://freepages.misc.rootsweb.ancestry.com/~taylorydna, and to explore the FTDNA websites--which together have a wealth of information about genetic genealogy and about the Taylor project.



To become a member, you'll need to go to FTDNA, http://www.ftdna.com/, and click on the "Products" tab at the top of the page and scroll down to the list of tests, then order a kit. There are many products available so we recommend our new members purchase the 37 DNA marker test (or the 67) because when you do get a match, it is easier to zoom in on the generation in which a common ancestor lived. These kits are for men. For Taylor women with no male Taylor to be tested, you have the option of following your maternal line, through testing mtDNA, or testing autosomal DNA, through the new Family Finder test. These two tests are also available to males.



Once your kit is turned in for processing there's about a 1 month waiting period for your results to come back. You can join the Taylor surname project at that time and we will request that you send your family tree to be posted on the site. Once your markers are in, FTDNA will post them and send you a certificate with all the data.



We hope this has given you the information to get you started. We look forward to you joining the 350 Taylors already participating in the project, who currently are sorted into about 35 family groups (i.e. related markers) and a number of "singles" awaiting family matches.

More Web Resources Available for You

Hi Again,

We have several projects underway that you will see soon enough. But in the meantime, here's an article, though the author calls it an e-book, that has some interesting information on Genetic Genealogy and gives many links.

There is a free document "I Have the Results of My DNA Test, Now What?" that you might find to be informative, that you can download from:

http://www.thegeneticgenealogist.com/

I will point out that I do not agree with this piece word-for-word. I'm letting you see it because it has much valuable material which might be helpful.

Lalia

37-Marker Matches and What They Mean

Hi,

What happens when you test 37 markers? Does a match of 36 out of 37 markers, commonly abbreviated as 36/37, mean more than 23/24?

Here is some more information from Ralph Taylor on what matches mean when we have 37 loci or markers to consider.

37-marker matches get even more precise. For example, if you share 35, 36 or 37 markers with another Taylor (or someone with your surname, if you are not looking at Taylor project results!) then you share a common ancestor, probably within a genealogic time frame.

o A perfect 37/37: The chances are 90% that your TMRCA is <= 19 generations, >= 1530 AD; 70% prob. is <= 10 gen, >= 1760 AD; 50% is <= 6 gen., >= 1860 AD.

o 36/37: 90% is <= 32 gen., >= 1210 AD; 70% is <= 20 gen., >= 1500 AD; 50% is <= 14 gen., >= 1660 AD.

o 35/37: 90% is <= 45 gen., >= 885 AD; 70% is <= 30 gen., >= 1260 AD; 50% is <= 22 gen., >= 1460 AD.

However when you have 37 markers to compare, and you don't match 35 or more, such as 33-34/37: You share a common ancestor, but probably not within a genealogic time frame.

§ 34/37: 90% is <= 57 gen., >= 580 AD; 70% is <= 40 gen., >= 1000 AD; 50% is <= 31 gen., >= 1235 AD.

§ 33/37: 90% is <= 69 gen., >= 285 AD; 70% is <= 50 gen., >= 760 AD; 50% is <= 40 gen., >= 1010 AD.

When we get to 32 matches out of 37, or worse: You may share a common ancestor, but the probability that he lived in within a genealogic time frame is small. The 50% probability level for a 32/37 match is <= 51 generations, >= 735 AD.

For some of you, these discussions of probability and statistics are dull. However, they are necessary to understand the meaning of genetic genealogy. We will have future posts with specific examples. For now, consider that your surname is Taylor. You have a family tree with some degree of confidence. Your fourth cousin, another male Taylor descended from the same line also tests. Now, if you match 37/37 or 36/37, this suggests that the family tree is correct for both of you. If, however, your match is 32/37 or less, the family tree is not correct for one or both of you. Because two males from the same male line, only separated by 6 generations would not differ to this extent.

May all your genealogical puzzles be solved!

Lalia

25-Marker Matches

What happens if/when we have 25-marker matches?

Well, the good news is that 25-marker matches allow finer interpretations:

· 24-25/25: You share a common ancestor, probably within a genealogic time frame. (The numbers of generations & dates below are approximate.)

¨ A perfect 25/25: The chances are 90% that your most recent common ancestor is within the past 28 generations, roughly since 1300 AD. It’s 70% that the time to the most recent common ancestor (TMRCA) is within 15 generations >= 1630 AD and 50% the TMRCA is <= 9 gen., >= 1780 AD. Thus, as we will find out when we look at greater numbers of markers, discovering a "perfect" 25/25 match only means that you share an ancestor who lived about 1300 (90% probability) to 1780 (50% probability).

A 24/25 match means even less. 24/25: The 90% probable TMRCA is <=48 gen, >= 800 AD; 70% is <= 30 gen., >= 1260 AD; 50% is <= 21 gen., >= 1480 AD.

Matching 23/25 may not illuminate your genealogical studies at all, as your common ancestor may have preceeded records with surnames. 23/25 or worse: You share a common ancestor, but he may not have lived within a genealogic time frame

Looking at this in terms of generations, instead of years, the match of 23/25: 90% TMRCA is <= 67 gen., >= 330 AD; 70% is <= 46 gen., >= 860; AD; 50% is <= 34 gen., >= 1160 AD.

While a 22/25 match means even less. 22/25: 90% TMRCA is <= 86 gen., >= 140 BC; 70% is <= 61 gen., >= 480 AD; 50% is <= 47 gen., >= 830 AD.

Input from Ralph Taylor and Lalia Wilson

What Does a 12 Marker Match Mean?

Here are some thoughts from Ralph Taylor on 12-marker Matches:

About 12-marker matches, there isn’t a lot to say. There are only three possibilities:

A perfect 12/12 means you share a common ancestor. But that ancestor may be many centuries in the past. The 90% probability level includes the past 60 generations (dating to as early as 510 AD); the 70% level includes the past 31 generations (as early as 1235 AD; and the 50% level (as likely to be low as high) includes the past 18 generations (as early as 1560 AD).

11/12 is inconclusive. Comparison of more markers is needed to draw any conclusions. If you are the one with only 12 markers tested, you should upgrade to more markers.

10/12 or worse excludes sharing a common ancestor within several thousands of years.

That’s cold, but true. 12 markers are considered sufficient to exclude sharing of a common ancestor, but not to include it.

Now, Lalia's interpretation... This means quite simply that if you match someone with the same surname 12 for 12, it suggests that you share that surname. However to trace your ancestry, you are going to need to test more markers and match more markers! (About which we will have more information in a future blog.)

If you do not share the same surname, or a variant of the surname, then a 12/12 match means that you likely come from the same general gene pool, such as the British Isles, and means nothing more.

We will have some forthcoming blog posts about higher levels of matches.

Good luck with your own genetic genealogical projects!

Lalia

Terminology Used in Genetic Genealogy

Hi,

Here are some terms that Ralph Taylor provides to help you understand your reading of articles and blog posts about genetic genealogy.

MRCA: The most recent common ancestor shared by two or more persons with a DNA match. We are concerned only with the most recent, because preceding ancestors will also be shared.

TMRCA: The probable time to the MRCA, expressed in generations.

Probability level: The cumulative probability, expressed as a percentage, that a MRCA lived within the specified number of generations. Here, we give three probability levels, 90%, 70%, & 50%. 90% means the chances are 9/10 the TMRCA is <= the given number; 50% probability is as likely to give a low TMRCA as a high one.

Genealogic time frame: A time for which it is feasible to specifically identify an ancestor, generally from about 1350 AD to the present.

Generations, length of: This is an estimated average of 25 years, developed from 18th and 19th century America statistics. We use the estimate to convert generations to common dates. Other societies may have had a different generational length -- either longer or shorter.

<=: Means less than or equal to, the maximum generations number for that probability level

>=: As applied to dates, means no earlier than the given date.