Opps, I forgot I could not embed links in the text. The web site is at: http://www.isogg.org/wiki/Autosomal_DNA_statistics ----- Original Message ----- From: Mike To: autosomal-dna@rootsweb.com Sent: Thursday, November 21, 2013 1:33 PM Subject: Re: [AUTOSOMAL-DNA] Finding shared atDNA ancestry without phasing If I understand your suspicion correctly, there is a table towards the bottom of this web site that correlates % IBD, % IBS vs cM. It essentially shows fro each cM below a 10 cM segment how quickly the probability of a true ancestral match drops to a match by identical state. Mike Z. ----- Original Message ----- From: peterebay@yahoo.com To: autosomal-dna-l@rootsweb.com Sent: Thursday, November 21, 2013 1:20 PM Subject: Re: [AUTOSOMAL-DNA] Finding shared atDNA ancestry without phasing I suspect a percentage estimate could be calculated for the likelihood of there NOT being shared ancestry when your matches on a particular 7+cM segment also all match each other on that segment. I would guess that it is less than one percent. This formula should include a variable for endogamy. I believe automated phasing is the ideal method. However very few people have the time or skill to use current procedures and tools. I contend that in the large majority of cases, you share a specific ancestral branch with your matches who all match each other on a specific atDNA segment measuring 7cM or greater. Sincerely, Peter Peter J. Roberts ______________________________ For answers to Frequently Asked Questions about mailing lists, please see: http://dgmweb.net/MailingListFAQs.html ------------------------------- To unsubscribe from the list, please send an email to AUTOSOMAL-DNA-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message

If I understand your suspicion correctly, there is a table towards the bottom of this web site that correlates % IBD, % IBS vs cM. It essentially shows fro each cM below a 10 cM segment how quickly the probability of a true ancestral match drops to a match by identical state. Mike Z. ----- Original Message ----- From: peterebay@yahoo.com To: autosomal-dna-l@rootsweb.com Sent: Thursday, November 21, 2013 1:20 PM Subject: Re: [AUTOSOMAL-DNA] Finding shared atDNA ancestry without phasing I suspect a percentage estimate could be calculated for the likelihood of there NOT being shared ancestry when your matches on a particular 7+cM segment also all match each other on that segment. I would guess that it is less than one percent. This formula should include a variable for endogamy. I believe automated phasing is the ideal method. However very few people have the time or skill to use current procedures and tools. I contend that in the large majority of cases, you share a specific ancestral branch with your matches who all match each other on a specific atDNA segment measuring 7cM or greater. Sincerely, Peter Peter J. Roberts

I suspect a percentage estimate could be calculated for the likelihood of there NOT being shared ancestry when your matches on a particular 7+cM segment also all match each other on that segment. I would guess that it is less than one percent. This formula should include a variable for endogamy. I believe automated phasing is the ideal method. However very few people have the time or skill to use current procedures and tools. I contend that in the large majority of cases, you share a specific ancestral branch with your matches who all match each other on a specific atDNA segment measuring 7cM or greater. Sincerely, Peter Peter J. Roberts ****Please include this message in any replies****

Constance, No. There is a roughly 50/50 chance that the Common Ancestor is through either parent of your Match. You know that your daughter's match is through you and your mother, because she has the same segment with you two. You know that your match is through your mother, because you both have the same segment with your Match. The Common Ancestor, however, could be through either of your mother's parents - you just have no clues at this point as to which of your mother's parents passed this segment down. You also have no clues about how your Match got this segment - which of her parents passed this segment down. If you or your mother have any other known relative who also matches on this segment, then that will tell you more information, depending on how you are related to the relative. The same is true with a Match - if he/she has a known relative who also match you on this segment, then that will tell the Match where the Common Ancestor is on his/her ancestry. atDNA lets us match cousins with any path (male/female mix) from the Common Ancestor, but this is a two edged sword... just because you know part of the path on your side, doesn't tell you anything about the path on the Matches side. Jim Bartlett On 11/21/13, Constance Shotts<ccts2013@carolina.rr.com> wrote: I have been reading all the discussions and trying to follow the threads, but this is a steep learning curve for me. I have a situation that I think I understand, but I want to see if I am on the right track if you will indulge me. My granddaugther, my daughter and myself have all been tested at 23andMe and have our results. There is an individual who is predicted as a 3rd to 5th cousin with all of us (but not yet proven genealogically). We all match on chromosome 1. The results show this person's matches to the three of us as follows: 29.3 cM (Genetic distance) 3846 (#SNPS) 27.6 cM (Genetic distance) 3580 (#SNPS) 10.6 cM (Genetic distance) 1429 (#SNPS) With the person matching all three generations on the same chromosome, we are sharing a common ancestor and likely on the maternal side for her as well as us. Is that correct?

Hi CeCe That is really the question. If I understand right, the fact that my granddaughter, my daughter and I all share the same match at the same location would indicate that the match came along maternal lines, or can I say that only as far as to myself? The notes on 23andMe state: "If you and your mom both have a segment in the same location, this shows that you got that segment from your mom and therefore are likely to be related to the common relative through your mom." Does that mean along the maternal line back to the common relative, or only back to me as the last in the line to have a test result? And what does it mean for the person who matches us? Can she be related on either the maternal or paternal line? -----Original Message----- From: autosomal-dna-bounces@rootsweb.com [mailto:autosomal-dna-bounces@rootsweb.com] On Behalf Of CeCe Moore Sent: Thursday, November 21, 2013 11:28 AM To: Autossomal DNA List Subject: Re: [AUTOSOMAL-DNA] Question based on results Hi Constance, Yes, it is a very steep learning curve - just keep reading all that you can. As to your question, why did you reach the conclusion that the match is most likely on both of your maternal lines? Best, CeCe Moore www.yourgeneticgenealogist.com > From: ccts2013@carolina.rr.com > To: autosomal-dna@rootsweb.com > Date: Thu, 21 Nov 2013 11:14:38 -0500 > Subject: [AUTOSOMAL-DNA] Question based on results > > I have been reading all the discussions and trying to follow the > threads, but this is a steep learning curve for me. I have a > situation that I think I understand, but I want to see if I am on the > right track if you will indulge me. > > My granddaugther, my daughter and myself have all been tested at > 23andMe and have our results. There is an individual who is predicted > as a 3rd to 5th cousin with all of us (but not yet proven > genealogically). We all match on chromosome 1. The results show this > person's matches to the three of us as > follows: > > 29.3 cM (Genetic distance) 3846 (#SNPS) > 27.6 cM (Genetic distance) 3580 (#SNPS) > 10.6 cM (Genetic distance) 1429 (#SNPS) > > > With the person matching all three generations on the same chromosome, > we are sharing a common ancestor and likely on the maternal side for > her as well as us. Is that correct? > > > > > > ------------------------------- > To unsubscribe from the list, please send an email to > AUTOSOMAL-DNA-request@rootsweb.com with the word 'unsubscribe' without > the quotes in the subject and the body of the message ______________________________ For answers to Frequently Asked Questions about mailing lists, please see: http://dgmweb.net/MailingListFAQs.html ------------------------------- To unsubscribe from the list, please send an email to AUTOSOMAL-DNA-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message

Connie, FTDNA has set the threshold for a match at 7cM - every match will have at least one segment that is 7cM long (and they'll have some other smaller, shared segments) The whole business of what's a good shared segment is a sliding scale of probabilities. There is NO fixed number for which all larger segments are from Common Ancestors and all smaller segments are not. FTDNA chose 7cM as a happy median - most such segments will be from Common Ancestors, but not all. Some people choose to use 10cM as a threshold, and in fact a higher percentage (but not 100%) of those will be from a Common Ancestor. Others use 5cM as a threshold (at GEDmatch, where you can set the threshold; or as a 2nd or 3rd segment for a Match at FTDNA). A higher percentage of these will be false or IBS (not from a Common Ancestor), but some more Matches and segments that are from Common Ancestors will be found. A lot depends on your goals... 1. If you want to map your genome - find specific segments from Ancestors to cover each of your 44 chromosomes - you should look for all the shared segments you can find (at 3 companies and GEDmatch) and set the threshold at 5cM. Then using Triangulation (and/or phasing), weed out as many of the IBS/bad segments as you can. 2. If you want to confirm much of your genealogy research and family lines, you might want to set the threshold at 10cM (or higher) and deal with fewer Matches. 3. If you are an adoptee, you'll probably only want to deal with much larger segments, hopefully from closer cousins, so you can focus on their families. 4. If you are focused on a particular brick wall, you might want a combination - using larger segments to work on a broad brush picture of your chromosomes and then perhaps use even 3cM shared segments that are on chromosomes and in areas that are probably where your brick wall is. You'd want to look at a lot of smaller segments in this are trying to find matches with ancestry that is beyond your brick wall (in place and time), so you can study those. 5. If you are looking for ancestry of a particular ethnicity, you would use the admixture tools (including several at GEDmatch), to find the general area(s) of your chromosome(s) that show that admixture, and again, lower your threshold to get all the shared segments and Matches that you can from that area(s). So as you can see there is not a single answer to your question that fits all situations. Same start or stop points can occur for several reasons: 1. These are the start/stop points of the segment you got from an ancestor (the start/stop points are recombination crossover points, and are fixed on each of your 44 chromosomes (randomly different on the chromosomes from Mom and Dad) - this is what you are hoping for... 2. These points may also be points on some chromosomes where the testing companies don't test (see grayed areas on the Browser) 3. These points may reflect the boundaries of blocks of SNPs FTNDA uses in their algorithms - they actually compare blocks of SNPs and the end points of shared segments are not really precise (think of sharpening a marshmallow) 4. And there are known crossover "hot spots" where breaks tend to occur - but that would be covered under #1 above. I don't understand "breaks in the segments". A shared segment is a contiguous string of SNPs - no breaks. If you mean gaps where the shared segments from several matches overlap, but don't exactly match up - well... the rule I use is they should overlap by 7cM, the same criteria as for a match. If there are several (say 5 in the chromosome browser, and they all look like lasagna - get the image?), then if they all share say 5cM it's a good bet they are a Triangulated Group (if the Matches match each other on that segment). If there isn't a clear 7cM overlap for all, it becomes a judgment call. If you have a bunch of segments in the same area of a chromosome for one person, they should wind up in two, well 3, groups - the person's Mom, the person's Dad, and IBS (neither). As with everything in random atDNA, it's possible to have something fall outside of these guidelines (say a 20cM IBS segment). The above works, but there are no absolute, 100% guarantees. Jim Bartlett On 11/21/13, Rvsailor@aol.com wrote: I am a project administrator of two atDNA projects. When dealing with a spread sheet of several ICW cousin matches downloaded from the GAP, should I discard all segments less than 10 cMs or should that number be closer to 7 cMs when the paperwork trail supports relationships? I initially went through the list and deleted everything below 10 but was concerned about discarding some of the 7, 8, and 9 matches as some had the same start or end points with others. Also, how should I handle matches on the same chromosome with breaks in the segments? Thanks. Connie Bradshaw John Carson of WNC Bradshaw & Harris

I have been reading all the discussions and trying to follow the threads, but this is a steep learning curve for me. I have a situation that I think I understand, but I want to see if I am on the right track if you will indulge me. My granddaugther, my daughter and myself have all been tested at 23andMe and have our results. There is an individual who is predicted as a 3rd to 5th cousin with all of us (but not yet proven genealogically). We all match on chromosome 1. The results show this person's matches to the three of us as follows: 29.3 cM (Genetic distance) 3846 (#SNPS) 27.6 cM (Genetic distance) 3580 (#SNPS) 10.6 cM (Genetic distance) 1429 (#SNPS) With the person matching all three generations on the same chromosome, we are sharing a common ancestor and likely on the maternal side for her as well as us. Is that correct?

I am a project administrator of two atDNA projects. When dealing with a spread sheet of several ICW cousin matches downloaded from the GAP, should I discard all segments less than 10 cMs or should that number be closer to 7 cMs when the paperwork trail supports relationships? I initially went through the list and deleted everything below 10 but was concerned about discarding some of the 7, 8, and 9 matches as some had the same start or end points with others. Also, how should I handle matches on the same chromosome with breaks in the segments? Thanks. Connie Bradshaw John Carson of WNC Bradshaw & Harris

Hi Constance, Yes, it is a very steep learning curve - just keep reading all that you can. As to your question, why did you reach the conclusion that the match is most likely on both of your maternal lines? Best, CeCe Moore www.yourgeneticgenealogist.com > From: ccts2013@carolina.rr.com > To: autosomal-dna@rootsweb.com > Date: Thu, 21 Nov 2013 11:14:38 -0500 > Subject: [AUTOSOMAL-DNA] Question based on results > > I have been reading all the discussions and trying to follow the threads, > but this is a steep learning curve for me. I have a situation that I think > I understand, but I want to see if I am on the right track if you will > indulge me. > > My granddaugther, my daughter and myself have all been tested at 23andMe and > have our results. There is an individual who is predicted as a 3rd to 5th > cousin with all of us (but not yet proven genealogically). We all match on > chromosome 1. The results show this person's matches to the three of us as > follows: > > 29.3 cM (Genetic distance) 3846 (#SNPS) > 27.6 cM (Genetic distance) 3580 (#SNPS) > 10.6 cM (Genetic distance) 1429 (#SNPS) > > > With the person matching all three generations on the same chromosome, we > are sharing a common ancestor and likely on the maternal side for her as > well as us. Is that correct? > > > > > > ------------------------------- > To unsubscribe from the list, please send an email to AUTOSOMAL-DNA-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message

Barbara As I understand it, they look at your DNA data in general and select some other persons data (called a reference sample) who might be a stand in for your parents and phase your data. The theory, as I get it, is that this pseudo-phasing is better than nothing and helps segregate out some IBS matches. I've looked at a lot of Ancestry matches who have uploaded to GEDmatch and match me there. I've tried to Triangulate them when several fall on overlapping segments - both among the Ancestry kits, and with kits from the other companies. Although a few do Triangulate (indicating IBD segments); a lot do not. Many (most) of my Ancestry matches at GEDmatch are in the bottom third of my list of matches there, with small segments which usually turn out to be IBS - I quit using them - even with Jeff's tool, I was usually unsuccessful in finding the Ancestry kits at GEDmatch who matched me, back on my Ancestry list. To say the least - I was not impressed with what they called phasing. Others may have a different view. Jim - Sent from my iPhone - FaceTime! On Nov 20, 2013, at 10:56 PM, "karenhappuch" <karenhappuch@cox.net> wrote: > How is phasing done without using parent/child or other close relatives? I > understand the Ancestry does this or attempts to do it, but how? How does > the program or procedure do the phasing and how accurate can it or could it > be? > Barbara > > ----- Original Message ----- > From: "Tim Janzen" <tjanzen@comcast.net> >> ...We need to move to >> phased data for these types of comparisons in the future. Hopefully >> 23andMe >> and FTDNA will eventually provide that for us. Hopefully Ancestry.com >> will >> eventually provide us with the HIR data and will improve the quality of >> their phased data....

Thanks, Tim, For those of us not using phasing techniques, and instead rely on various segment rules, I think the Triangulation technique is still an excellent tool. Using the utilities at 23andMe, GEDmatch and FTDNA, along with the closest cousins I can find (with known MRCAs), and working with every Match I can find with segment data, I now have about 80 percent of my atDNA segments assigned to a parent. When I say "my atDNA segments", I mean pseudo-segments which are a combination of segments from Matches. For example, if I can Triangulate A (21-34Mbp); B (22-45Mbp); C (25-36Mbp); D (27-52MBp) on one Chr, then I create a pseudo-segment (21-52Mbp) which is what I got from our Common Ancestor. In comparing A B C D to each other I usually find that their shared segments are cover more than the segment I got. This is OK - it just means our Common Ancestor started out with a segment that was, say (15-60Mbp) and different ones of us got different, but overlapping parts of it. Thanks again for providing some real- world insight on the question at hand. If I ever find such an anomaly, I'll be sure to report it. None yet. Jim - Sent from my iPhone - FaceTime! On Nov 21, 2013, at 1:36 AM, "Tim Janzen" <tjanzen@comcast.net> wrote: > Dear Jim, > In my case, the question is whether or not the 6.5 cM segment came > down through person #10 or person #15 on my mom's grandmother's pedigree > chart, an older version of which may be seen at > http://wc.rootsweb.ancestry.com/cgi-bin/igm.cgi?op=PED&db=janzen&id=I8. The > 6.5 cM segment could have come from a different ancestor than the rest of > the 21.7 cM segment. I don't personally get entangled in situations like > the one you raise because I am already segregating my parents matches on any > one segment of an isolated chromosome before I compare them to each other. > I do that by separating those matches into those who also match me as > compared to those who do not match me. This separates the matches into > those matching on one chromosome and those matching on the opposite > chromosome. Therefore in my parents' match lists I am never comparing A to > B as in your situation. In any case, your situation will occur at least on > rare occasion. I haven't seen that exact situation, however. > Sincerely, > Tim > > -----Original Message----- > From: autosomal-dna-bounces@rootsweb.com > [mailto:autosomal-dna-bounces@rootsweb.com] On Behalf Of Jim Bartlett > Sent: Wednesday, November 20, 2013 8:19 PM > To: autosomal-dna@rootsweb.com > Subject: Re: [AUTOSOMAL-DNA] Finding shared atDNA ancestry without phasing > > > Tim, > > So you have Mom has HIR with A(21.7) > Mom has HIR on same segment with B(6.5) > and A has an HIR on same segment with B > > This is classic genetic Triangulation. > > Is there any reason to believe there is more than one Common Ancestor for > the 3 of them? > > The possibility that we are studying is: > > Mom & A have an IBD HIR from Mom's Dad and A's Mom > Mom & B have an IBD HIR from Mom's Mom and B's Mom > A & B have an IBD HIR from A's Dad and B's Dad > All 3 IBD HIRs are on essentially the same location on the same > chromosome > number. > All 3 pairs would probably have different MRCAs. > > This is technically possible. The question is what is the probability. > I've > not seen it (that I recognize), yet. > > Jim Bartlett

Dear Jim, In my case, the question is whether or not the 6.5 cM segment came down through person #10 or person #15 on my mom's grandmother's pedigree chart, an older version of which may be seen at http://wc.rootsweb.ancestry.com/cgi-bin/igm.cgi?op=PED&db=janzen&id=I8. The 6.5 cM segment could have come from a different ancestor than the rest of the 21.7 cM segment. I don't personally get entangled in situations like the one you raise because I am already segregating my parents matches on any one segment of an isolated chromosome before I compare them to each other. I do that by separating those matches into those who also match me as compared to those who do not match me. This separates the matches into those matching on one chromosome and those matching on the opposite chromosome. Therefore in my parents' match lists I am never comparing A to B as in your situation. In any case, your situation will occur at least on rare occasion. I haven't seen that exact situation, however. Sincerely, Tim -----Original Message----- From: autosomal-dna-bounces@rootsweb.com [mailto:autosomal-dna-bounces@rootsweb.com] On Behalf Of Jim Bartlett Sent: Wednesday, November 20, 2013 8:19 PM To: autosomal-dna@rootsweb.com Subject: Re: [AUTOSOMAL-DNA] Finding shared atDNA ancestry without phasing Tim, So you have Mom has HIR with A(21.7) Mom has HIR on same segment with B(6.5) and A has an HIR on same segment with B This is classic genetic Triangulation. Is there any reason to believe there is more than one Common Ancestor for the 3 of them? The possibility that we are studying is: Mom & A have an IBD HIR from Mom's Dad and A's Mom Mom & B have an IBD HIR from Mom's Mom and B's Mom A & B have an IBD HIR from A's Dad and B's Dad All 3 IBD HIRs are on essentially the same location on the same chromosome number. All 3 pairs would probably have different MRCAs. This is technically possible. The question is what is the probability. I've not seen it (that I recognize), yet. Jim Bartlett

Tim, So you have Mom has HIR with A(21.7) Mom has HIR on same segment with B(6.5) and A has an HIR on same segment with B This is classic genetic Triangulation. Is there any reason to believe there is more than one Common Ancestor for the 3 of them? The possibility that we are studying is: Mom & A have an IBD HIR from Mom's Dad and A's Mom Mom & B have an IBD HIR from Mom's Mom and B's Mom A & B have an IBD HIR from A's Dad and B's Dad All 3 IBD HIRs are on essentially the same location on the same chromosome number. All 3 pairs would probably have different MRCAs. This is technically possible. The question is what is the probability. I've not seen it (that I recognize), yet. Jim Bartlett On 11/20/13, Tim Janzen<tjanzen@comcast.net> wrote: Dear Jim, The match who shares the HIR that is 21.7 cMs long with my mom also appears as a match on the same segment of chromosome 7 in Family Inheritance: Advanced at 23andMe with the person who shares the 6.5 cM HIR with my mom. I don't have the raw data files for these two matches, but I believe it is highly probable that the HIRs are both IBD given that my brother also shares the same HIRs with both people. We need to move to phased data for these types of comparisons in the future. Hopefully 23andMe and FTDNA will eventually provide that for us. Hopefully Ancestry.com will eventually provide us with the HIR data and will improve the quality of their phased data. I think it is important to note that it is essentially impossible for two or more people to share a phased autosomal haplotype of any significant length and have them get it from different ancestral lines. The phased haplotype must have come from a shared ancestor at some point in the past. However, that shared ancestor isn't always apparent to the testees. Sincerely, Tim -----Original Message----- From: a[1]utosomal-dna-bounces@rootsweb.com [[2]mailto:autosomal-dna-bounces@rootsweb.com] On Behalf Of Jim Bartlett Sent: Wednesday, November 20, 2013 5:17 AM To: [3]autosomal-dna@rootsweb.com Subject: Re: [AUTOSOMAL-DNA] Finding shared atDNA ancestry without phasing Tim Thanks for the examples. Four thoughts for all: 1. Tim didn't mention if the Matches matched each other, on this segment. We are particularly looking for 3 people who all match each other on one segment, and each pair got their atDNA from a different ancestral line. This is very rare, and we're trying to see if anyone has documented this, or if it is so rare that we can dismiss the possibility. 2. As we get beyond close cousins, we'll find there are shared segments and shared ancestry, but the shared ancestry is not from the shared segments. I have many of these cases, including one yesterday: my maternal uncle, Nathan Baker, did Y-DNA 10 years ago and helped prove the "Gunsmith" BAKER line; last night's atDNA match is also a Y-DNA match on this BAKER line - so we are definitely 7th cousins on my maternal BAKERs. Except in my atDNA spreadsheet I've got several folks who match him, who also match my Dad (5-way Triangulation); and a bunch of other folks with close cousinship on my Mom's side, whom he does not match. It is clear to me that this new Baker match and I have another Common Ancestor on my Dad's side, per the atDNA segment... Jim - Sent from my iPhone - FaceTime! References 1. mailto:utosomal-dna-bounces@rootsweb.com 2. mailto:autosomal-dna-bounces@rootsweb.com 3. mailto:autosomal-dna@rootsweb.com

How is phasing done without using parent/child or other close relatives? I understand the Ancestry does this or attempts to do it, but how? How does the program or procedure do the phasing and how accurate can it or could it be? Barbara ----- Original Message ----- From: "Tim Janzen" <tjanzen@comcast.net> > ...We need to move to > phased data for these types of comparisons in the future. Hopefully > 23andMe > and FTDNA will eventually provide that for us. Hopefully Ancestry.com > will > eventually provide us with the HIR data and will improve the quality of > their phased data.... \

Dear Jim, The match who shares the HIR that is 21.7 cMs long with my mom also appears as a match on the same segment of chromosome 7 in Family Inheritance: Advanced at 23andMe with the person who shares the 6.5 cM HIR with my mom. I don't have the raw data files for these two matches, but I believe it is highly probable that the HIRs are both IBD given that my brother also shares the same HIRs with both people. We need to move to phased data for these types of comparisons in the future. Hopefully 23andMe and FTDNA will eventually provide that for us. Hopefully Ancestry.com will eventually provide us with the HIR data and will improve the quality of their phased data. I think it is important to note that it is essentially impossible for two or more people to share a phased autosomal haplotype of any significant length and have them get it from different ancestral lines. The phased haplotype must have come from a shared ancestor at some point in the past. However, that shared ancestor isn't always apparent to the testees. Sincerely, Tim -----Original Message----- From: autosomal-dna-bounces@rootsweb.com [mailto:autosomal-dna-bounces@rootsweb.com] On Behalf Of Jim Bartlett Sent: Wednesday, November 20, 2013 5:17 AM To: autosomal-dna@rootsweb.com Subject: Re: [AUTOSOMAL-DNA] Finding shared atDNA ancestry without phasing Tim Thanks for the examples. Four thoughts for all: 1. Tim didn't mention if the Matches matched each other, on this segment. We are particularly looking for 3 people who all match each other on one segment, and each pair got their atDNA from a different ancestral line. This is very rare, and we're trying to see if anyone has documented this, or if it is so rare that we can dismiss the possibility. 2. As we get beyond close cousins, we'll find there are shared segments and shared ancestry, but the shared ancestry is not from the shared segments. I have many of these cases, including one yesterday: my maternal uncle, Nathan Baker, did Y-DNA 10 years ago and helped prove the "Gunsmith" BAKER line; last night's atDNA match is also a Y-DNA match on this BAKER line - so we are definitely 7th cousins on my maternal BAKERs. Except in my atDNA spreadsheet I've got several folks who match him, who also match my Dad (5-way Triangulation); and a bunch of other folks with close cousinship on my Mom's side, whom he does not match. It is clear to me that this new Baker match and I have another Common Ancestor on my Dad's side, per the atDNA segment... Jim - Sent from my iPhone - FaceTime!

Jim's explanation gives a nice clear summary for those who are just starting to grapple with identifying segments and ancestors connected with them. Many of our matches really don't yet understand much about how any of this works--they are new to DNA, or haven't yet been pointed in helpful directions such as this list, and it's important for us to give them easy pointers when there is email or message contact. I'm sure everyone on this list has received at least one message like the one I got last night from a 23andMe match who hadn't even yet "shared" genomes but wanted to know how closely we were related. Of course, at that point all I could say was that the relationship was 4th cousin or farther and that it could involve one of at least three nationalities. While I don't give lessons to every single DNA match, I do feel it's important to help matches who ask or who obviously aren't clear on the concepts, and would encourage everyone here to do the same in small, easily digestible chunks, with URLs for further info, etc. Little bits of education from a lot of us will ultimately make a big difference. Karla On Wed, Nov 20, 2013 at 10:41 AM, Jim Bartlett <jim4bartletts@verizon.net>wrote: > > Eric, > > Yours is the same aha moment that everyone interested in segments or > mapping > needs to understand. >

Eric, Yours is the same aha moment that everyone interested in segments or mapping needs to understand. You have two of each atDNA chromosome - one from Mom, one from Dad. Each one is filled with segments that came from the respective parent's ancestors. When you have a shared segment with a Match, or see a segment on a chromosome browser, you cannot tell which one of the two chromosomes it is on (the one you got from Mom or the one you got from Dad) Each the two chromosomes (one from Mom, one from Dad) has a different random arrangement of segments - some are overlapping, some are in roughly the same location (the location is noted by a start position and a stop position) So, just because two shared segments have the same (or similar) start and end points (or are closely overlapping), they could be on the same chromosome (from Mom or Dad), or each one could be on a different chromosome (one on the chromosome from Mom, one on the chromosome from Dad). If the Matches who share the two segments above match each other, then the two segments are on the same chromosome (it would be a very, very unlikely happenstance to have such segments on different chromosomes match each other). As such you and the two Matches will have the same Common Ancestor. This is called genetic Triangulation, and the three of you are in a Triangulated Group. If the Matches who share the two segments above, do not match each (and the segments with your are long enough and overlap enough that they reasonably should match if they were on the same chromosome), then it is safe to assume that they are from different chromsomes (one is from the chromosome from Mom, the other from Dad) If any of the folks in a Triangulated Group is a close relative, then that TG, and all the segments in it can be assigned to the appropriate parent (Mom or Dad); and the segments which clearly don't match anyone in the TG (but should if they were on the same chromosome) can be assigned to the other parent. Triangulated Groups are particularly important to adoptees and folks with brick walls because if any two people in the TG can determine the MRCA for the TG, then that ancestral line will apply to everyone in the TG. Notice I said "ancestral line" - some in the TG may not have the same MRCA, but all will have a Common Ancestor whose descendants include all the MRCAs in the TG. In other words two 2nd cousins will have great grandparents in common; another Match who is in a TG with these 2nd cousins, may be a 4th cousin and have 3G grandparents in common, but the 3G grandparents will be ancestors of the G grandparents the 2nd cousins share. For shared segments, there needs to be a path from a Common Ancestor down to each Match in a TG. Hope this helps your aha... Jim Bartlett On 11/20/13, Eric S Johnson<crates@oneotaslopes.org> wrote: > From: a[1]utosomal-dna-bounces@rootsweb.com [[2]mailto:autosomal-dna- > [3]bounces@rootsweb.com] On Behalf Of Tim Janzen > Sent: Wednesday, November 20, 2013 03.32 > Then about 3 weeks ago my mom got another match on this same segment > from someone who has Bigelow ancestry. So it's possible to have an "identical" match with two different "genetic relatives" on (more or less) the same "chromosomal segment," but have these matches be a result of two different MRCAs--one on one half of the chromosome (HIR), one on the other? Sorry ... I'm having one of those "aha" moments ... Best, Eric References 1. mailto:utosomal-dna-bounces@rootsweb.com 2. mailto:autosomal-dna- 3. mailto:bounces@rootsweb.com

Tim Thanks for the examples. Four thoughts for all: 1. Tim didn't mention if the Matches matched each other, on this segment. We are particularly looking for 3 people who all match each other on one segment, and each pair got their atDNA from a different ancestral line. This is very rare, and we're trying to see if anyone has documented this, or if it is so rare that we can dismiss the possibility. 2. As we get beyond close cousins, we'll find there are shared segments and shared ancestry, but the shared ancestry is not from the shared segments. I have many of these cases, including one yesterday: my maternal uncle, Nathan Baker, did Y-DNA 10 years ago and helped prove the "Gunsmith" BAKER line; last night's atDNA match is also a Y-DNA match on this BAKER line - so we are definitely 7th cousins on my maternal BAKERs. Except in my atDNA spreadsheet I've got several folks who match him, who also match my Dad (5-way Triangulation); and a bunch of other folks with close cousinship on my Mom's side, whom he does not match. It is clear to me that this new Baker match and I have another Common Ancestor on my Dad's side, per the atDNA segment... 3. With Colonial Virginia ancestry, I have several Matches with multiple Common Ancestors. Like Tim, I label them as ALTs until I can Triangulate on the genealogy side. 4. With a large segment (and usually closer cousinship), we can pretty much count on that segment splitting, somewhere, into two smaller branches, both ancestral to the first. This is rational as we get one large segment from a parent (covers the whole chromosome); which we find is split into a few large segments from each grandparent; and those are further split into segments from the great grandparents; etc. (these splits are the crossover points). Sometimes they are found in the next generation (going back into the ancestry), and sometimes the segment stays pretty much in tact for several generations (going back), before it is split. The limit on splitting, of course, is the 7cM threshold as a Match is not reported below that level (except at GEDmatch), so we never "see" the next split. Actually, the above discussion is from my perspective as a living descendant looking back. What really happens is the atDNA from our ancestors is passed down, and new segments are created ! from the parents of each ancestor through recombination. This is the split that we see looking back. And this is why it will take about 500 discrete segments, each assigned to an ancestral couple (usually), to map our 44 atDNA chromosomes. The ancestral couple will be split apart, going back, into a even smaller segments we may find at GEDmatch. Jim - Sent from my iPhone - FaceTime! On Nov 20, 2013, at 3:31 AM, "Tim Janzen" <tjanzen@comcast.net> wrote: > Dear Jim, > I have a situation I came across about 3 weeks ago that is similar > to what you are looking for. There is a segment on chromosome 7 that my mom > shares with her 2nd cousin. I thus know that this segment was passed to my > mom from her paternal grandmother Anna B. Armstrong (b. 1876). About 3 > months ago I got a match on this segment from someone who has Dewey Ancestry > on two ancestral lines. The HIR is 21.7 cMs long and contains 4074 SNPs, > which is unlikely to be IBS. This was nice since Anna B. Armstrong has > Dewey ancestry through Sally Dewey (b. 1781). This person is both a 5th > cousin and a 6th cousin through the Dewey line. I thus mapped this > particular segment on my mom's chromosome map to Sally Dewey. Then about 3 > weeks ago my mom got another match on this same segment from someone who has > Bigelow ancestry. This person is a 5th cousin once removed on the Bigelow > line. The HIR is shorter at 6.5 cMs but it contains 1398 SNPs and is also > found in my brother, which makes it unlikely to be IBS. Thus, the segment > in question could have come down through Russel Bigelow (b. 1763). Both > Russel Bigelow and Sally Dewey are ancestors of Anna B. Armstrong on > different ancestral lines. This certainly gave me pause since I am now not > certain exactly which ancestral line from which this particular segment was > passed to Anna B. Armstrong. I have decided to label this particular > segment as being from either Russel Bigelow or Sally Dewey until I get other > matches on this segment that help me better sort this situation out. There > are a number of possibilities here: > 1. My mom's match with Dewey ancestry has Bigelow (or another allied > ancestral surname) ancestry in their pedigree chart somewhere. > 2. My mom's match with Bigelow ancestry has Dewey (or another allied > ancestral surname) ancestry in their pedigree chart somewhere. > 3. The 6.5 cM portion of the segment came through the Bigelow line and the > match with Dewey ancestry also has Bigelow (or another allied ancestral > surname) ancestry while the other portion of the segment came through the > Dewey line. > > I think we will find more of these types of situations in the future as we > all do more chromosome mapping. > Sincerely, > Tim Janzen >

> From: autosomal-dna-bounces@rootsweb.com [mailto:autosomal-dna- > bounces@rootsweb.com] On Behalf Of Tim Janzen > Sent: Wednesday, November 20, 2013 03.32 > Then about 3 weeks ago my mom got another match on this same segment > from someone who has Bigelow ancestry. So it's possible to have an "identical" match with two different "genetic relatives" on (more or less) the same "chromosomal segment," but have these matches be a result of two different MRCAs--one on one half of the chromosome (HIR), one on the other? Sorry ... I'm having one of those "aha" moments ... Best, Eric

Dear Jim, I have a situation I came across about 3 weeks ago that is similar to what you are looking for. There is a segment on chromosome 7 that my mom shares with her 2nd cousin. I thus know that this segment was passed to my mom from her paternal grandmother Anna B. Armstrong (b. 1876). About 3 months ago I got a match on this segment from someone who has Dewey Ancestry on two ancestral lines. The HIR is 21.7 cMs long and contains 4074 SNPs, which is unlikely to be IBS. This was nice since Anna B. Armstrong has Dewey ancestry through Sally Dewey (b. 1781). This person is both a 5th cousin and a 6th cousin through the Dewey line. I thus mapped this particular segment on my mom's chromosome map to Sally Dewey. Then about 3 weeks ago my mom got another match on this same segment from someone who has Bigelow ancestry. This person is a 5th cousin once removed on the Bigelow line. The HIR is shorter at 6.5 cMs but it contains 1398 SNPs and is also found in my brother, which makes it unlikely to be IBS. Thus, the segment in question could have come down through Russel Bigelow (b. 1763). Both Russel Bigelow and Sally Dewey are ancestors of Anna B. Armstrong on different ancestral lines. This certainly gave me pause since I am now not certain exactly which ancestral line from which this particular segment was passed to Anna B. Armstrong. I have decided to label this particular segment as being from either Russel Bigelow or Sally Dewey until I get other matches on this segment that help me better sort this situation out. There are a number of possibilities here: 1. My mom's match with Dewey ancestry has Bigelow (or another allied ancestral surname) ancestry in their pedigree chart somewhere. 2. My mom's match with Bigelow ancestry has Dewey (or another allied ancestral surname) ancestry in their pedigree chart somewhere. 3. The 6.5 cM portion of the segment came through the Bigelow line and the match with Dewey ancestry also has Bigelow (or another allied ancestral surname) ancestry while the other portion of the segment came through the Dewey line. I think we will find more of these types of situations in the future as we all do more chromosome mapping. Sincerely, Tim Janzen -----Original Message----- From: autosomal-dna-bounces@rootsweb.com [mailto:autosomal-dna-bounces@rootsweb.com] On Behalf Of Jim Bartlett Sent: Tuesday, November 19, 2013 9:46 AM To: KATHRYN JOHNSTON; autosomal-dna@rootsweb.com Subject: Re: [AUTOSOMAL-DNA] Finding shared atDNA ancestry without phasing Is there anyone on this list who has experienced a case of three people matching each other on the same segment, and determining that at least two pairs of them have different Common Ancestors? Perhaps we can find some real life examples... Jim -