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Author Topic: Understanding the 12 marker study from Family Tree DNA  (Read 1335 times)
johnfnewman
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« on: February 20, 2008, 12:22:17 PM »

I recently got back the results of the 12 marker test on my father's genetics from FamilyTree DNA.

I need a bit of help understanding the results.  A list of 176 people were provided to me who were a 12/12 match.  All but one had a different surname (I attempted to contact that person, but to no avail).

As I browsed through the list, several surnames repeated several times.

My question is this: what relevance are those 12/12 matches with 175 other people with different surnames?  I am awaiting the results of the other tests, but my understanding is that I may be related to these other 175 people but that the relation is so distant it even isn't worth considering.

I also had an 11/12 match with another person of the same surname.  Despite being a 12/12 match with people of another surname, I am under the impression that I am more closely related to the 11/12 match with the person of the same surname.  Am I getting this right? While I am waiting for the other tests to be completed, is it even worth bothering about the 12/12 study?

The short synopses of these tests provided by the company and elsewhere leave me scratching my head.

thanks for any help

- John
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Marilyn Teaff Barton
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« Reply #1 on: February 21, 2008, 08:51:04 PM »

Hi, John.  Here is how we usually tell people to analyze their matches at 12 markers: 
Matches of less than 9/12 – the two participants do not share a common ancestor*
Matches of 9/12 - there is a tiny chance that the participants share a common ancestor. You'll need to test at 37 markers to find a true shared genetic match that starts with such a low match. (The author has not yet seen a 9/12 become an accepted genetic match - but has heard of one case)
Matches of 10/12 – there is a small chance that the participants share a common ancestor. Increase to 25 markers and re-evaluate
Matches of 11/12 and 12/12 – there is an improved chance that the participants share a common ancestor. Increase to 25 markers and re-evaluate
CAUTION: a 12/12 match - even with the same surname - can be a random match. If a solid paper trail connects the 12/12 match, you can be reasonably certain of shared ancestry, but without the connecting paper trail - you can only be sure by upgrading to at least 25 markers

As you have probably already concluded, a 12 marker match cannot be considered conclusive.  As you have already ordered more markers, I would sugges that you wait until your other results are ready and re-evaluate your matches at that time.  For more information about understanding your results, take a look at this page:  http://worldfamilies.net/understandresults.html
And to make sure you make the best use of the services at FTDNA, this page explains your Personal Page:  http://worldfamilies.net/personalpageinfo.html
For a step by step guide to DNA Testing:  http://worldfamilies.net/dnatestingthesmartway.html
Hope that helps.
Marilyn
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sbward
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« Reply #2 on: February 26, 2008, 06:46:26 PM »

You really need more than 12 markers to tell you anything - you should try smgf.org which tests at least 30 markers for both Y-DNA and mtDNA free. 

If a match doesn't have your same last name and you weren't adopted, it's either one of 2 things:
1. this person has no relation to you whatsoever.
2. one of your male ancestors is not who you think it is.
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johnfnewman
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« Reply #3 on: February 26, 2008, 10:01:23 PM »

You really need more than 12 markers to tell you anything - you should try smgf.org which tests at least 30 markers for both Y-DNA and mtDNA free. 

If a match doesn't have your same last name and you weren't adopted, it's either one of 2 things:
1. this person has no relation to you whatsoever.
2. one of your male ancestors is not who you think it is.

Here is my problem, I have had a very difficult time trying to figure out who my grandfather's grandparents were.  The family story was that my grandfather's father was disowned.  I've become so frustrated with finding who my ancestor Newmans are, that I started to think that "New-Man" was a ade up surname for someone looking to start fresh.

I am waiting for results on my 67 marker test.

The question is: for different surnames, how much of a match should I be looking for undedr No. 2 above: "one of your male ancestors is not who you think it is"?  How many matches out of 67 markers do I start to think that I may want to investigate another surname?
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sbward
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« Reply #4 on: February 26, 2008, 11:04:01 PM »

I matched my paternal markers 28/29 with someone on smgf.org who traces his ancestry back to the same man I do, born in 1506.  I'd call that quite a coincidence if we are not related.  There is also a person of a different surname whom I match 27/29 and I would bet that 2nd person is not descended from the person he thinks he is.

There are several other sites where you can enter your markers and find matches - ysearch.org, ancestry.com, ybase.org - I would try them all once you get your 67 markers, and see if the same name comes up more than once.  On many sites, you won't find people who have that many markers tested - it will be more like 30-40. 

I'm no expert so I can't tell you how many you have to match, but generally it shouldn't be off more than 3 markers of the ones tested.

In my opinion, FTDNA is ripping people off with a 12-marker test because it just doesn't tell you anything.  Did it even tell you your haplogroup?
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