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 - Sent from my iPhone - FaceTime! On Nov 19, 2013, at 12:19 PM, KATHRYN JOHNSTON <kathryn.johnston@sbcglobal.net> wrote: > I don't think there has been a lot of phased studies. It is something that simply needs to be done. > > > A four way match in an endogamous group could have: > AB > AB > BC > AC > > They all match each other but you should see fully identical matching for the first two. You would have to look at a chromosome browser that shows the fully identical (double-stranded) segments. This is one more reason to have these kinds of browsers made more readily available by the testing companies. This is the only situation that I can think of that would cause a complete four-way match. > > I think that if everyone matches everyone else and you have a robust match with all four people with no full matching, and no endogamy or consanguinity, then you are most likely dealing with a single lineage and not the above situation. > > But when dealing with a close-knit heavily drifted community, I would still be on the look-out for these rare birds. I have certainly heard of cases where ALMOST everybody matched everybody else. There could have been threshold issues, mutations, SNP poor regions, errors, IBS etc. instead of IBD endogamy but how would you know if you don't look at the phased raw data and pinned the segment on a specific ancestor? A situation where there are multiple matches, but not sharing with everyone might be: AD, AC, BC, AB, CD, BD. Each of the 6 people matches with four other people and does not match with one. It could fool you into believing that everyone comes from the same MRCA even though there are four ancestors that provided matching segments within the same two position numbers. We all know of groups of ancestors who were highly proliferative. > > It is extremely important to make sure that everyone matches everyone else as you say when dealing with 4 or more people. But with 3 people, there is no guarantee you have a single ancestral line (even if they do all match each other) without phasing them and/or clear identification of the line. > > People need to study this further in a real life situations. Right now we are only dealing with a hypothetical problem. > Kathy > > ------ >> Hello Kathy, >> >> What if the ancestry is NOT from an >> endogamous group? What if it is from an >> endogamous group but is a 4 way match? - >> Where all the matches are matching each other? >> Thanks and sincerely, Peter >

If this fits your situation.... I match two of my cousins on the same segment on the same chromosome, but one is from my mother's line and one from my dad's as they are known cousins and my parents aren't related. If this fits your needs, I can send more detail. E If you do not hear from me in a timely manner, just write again...I was buried in email.  LOL http://writingyourmemories.blogspot.com/ http://www.rootsweb.com/~orgco2/speaker/EmilyAulicino.html http://genealem-geneticgenealogy.blogspot.com/ Northwest Regional Coordinator and Speaker for ISOGG (www.isogg.org) Administrator for thirteen FTDNA DNA Projects -----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 - Sent from my iPhone - FaceTime! On Nov 19, 2013, at 12:19 PM, KATHRYN JOHNSTON <kathryn.johnston@sbcglobal.net> wrote: > I don't think there has been a lot of phased studies. It is something that simply needs to be done. > > > A four way match in an endogamous group could have: > AB > AB > BC > AC > > They all match each other but you should see fully identical matching for the first two. You would have to look at a chromosome browser that shows the fully identical (double-stranded) segments. This is one more reason to have these kinds of browsers made more readily available by the testing companies. This is the only situation that I can think of that would cause a complete four-way match. > > I think that if everyone matches everyone else and you have a robust match with all four people with no full matching, and no endogamy or consanguinity, then you are most likely dealing with a single lineage and not the above situation. > > But when dealing with a close-knit heavily drifted community, I would still be on the look-out for these rare birds. I have certainly heard of cases where ALMOST everybody matched everybody else. There could have been threshold issues, mutations, SNP poor regions, errors, IBS etc. instead of IBD endogamy but how would you know if you don't look at the phased raw data and pinned the segment on a specific ancestor? A situation where there are multiple matches, but not sharing with everyone might be: AD, AC, BC, AB, CD, BD. Each of the 6 people matches with four other people and does not match with one. It could fool you into believing that everyone comes from the same MRCA even though there are four ancestors that provided matching segments within the same two position numbers. We all know of groups of ancestors who were highly proliferative. > > It is extremely important to make sure that everyone matches everyone else as you say when dealing with 4 or more people. But with 3 people, there is no guarantee you have a single ancestral line (even if they do all match each other) without phasing them and/or clear identification of the line. > > People need to study this further in a real life situations. Right now we are only dealing with a hypothetical problem. > Kathy > > ------ >> Hello Kathy, >> >> What if the ancestry is NOT from an >> endogamous group? What if it is from an endogamous group but is a 4 >> way match? - Where all the matches are matching each other? >> Thanks and sincerely, Peter > ______________________________ 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

Emily Yes, this is common. Do the two cousins match each other on the same segment? That is what we are looking for. Jim - Sent from my iPhone - FaceTime! On Nov 20, 2013, at 12:10 AM, "Emily Aulicino" <aulicino@hevanet.com> wrote: > If this fits your situation.... > > I match two of my cousins on the same segment on the same chromosome, but > one is from my mother's line and one from my dad's as they are known cousins > and my parents aren't related. > > If this fits your needs, I can send more detail. > > E >

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 -