Dear Melissa, I think it is important that we keep in mind the information that Ann Turner and I posted on this topic back in January. See my message at http://archiver.rootsweb.ancestry.com/th/read/AUTOSOMAL-DNA/2012-01/13260977 07 for a summary of my analysis. Even at 3.5-4 cMs it would appear that about 17% of matching segments are IBD. We need to have other people generate similar statistics to what I generated and we then need to pool the data to get an even clearer picture about the IBD versus IBS situation. Unfortunately, none of the DNA companies doing autosomal DNA analysis are providing statistics on a large scale for the IBD versus IBS situation similar to what I provided in the message above. In any case, I think that my data still provides significant insight into this. Accurate chromosome mapping is imperative and if you have created accurate chromosome maps for all of these people using data from first, second, and third cousins then you will be in a better position to determine which of these 3-5 cM HIRs are IBD. Using phased data for all of these people when you run the comparisons against Mister X would also be of major help to you in this situation, assuming that Mister X would be willing to share his raw data file with you. Sincerely, Tim Janzen -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of M Robards Sent: Thursday, May 24, 2012 11:00 PM To: [email protected] Subject: [AUTOSOMAL-DNA] IBD and IBS Revisited :( Scattered through out the other chromosomes are small sets of matching segments, most either with 1,2 and 3, or 2, 3 and 4. Normally I would think these are mainly IBS, but in this case where I have these specific 4 testers, and they share many of the smaller segments, isn't there a good chance many/most of these smaller 'matches' are also IBD? There are several combinations of the 4 matching Mister X, but no match ever includes #1 and #4 together. One example of a small matching segment, Chr 6: #1 @ 129879242 - 132216752, 3.15, 700 #3 @ 129879242 - 132216752, 3.15, 700 Since #1 and #3 share the same mother but not the same father, this would come from the mother's side, so are these small matching segments more likely to be IBS or IBD? melissa springer robards

Thank you so much, Tim. Typical of me to not remember that thread at all. It helps immensely to put things back into perspective. Huge thread, though, I think I need some coffee now so I can get started reading all the posts in it :) melissa On Thu, May 24, 2012 at 11:36 PM, Tim Janzen <[email protected]> wrote: > Dear Melissa, snip See my message at > http://archiver.rootsweb.ancestry.com/th/read/AUTOSOMAL-DNA/2012-01/1326097707 for a summary of my analysis.  Even at 3.5-4 cMs it would appear that > about 17% of matching segments are IBD.  We need to have other people > generate similar statistics to what I generated and we then need to pool the > data to get an even clearer picture about the IBD versus IBS situation. snip Accurate chromosome> mapping is imperative and if you have created accurate chromosome maps for> all of these people using data from first, second, and third cousins then> you will be in a better position to determine which of these 3-5 cM HIRs are> IBD. snip > Tim Janzen > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of M Robards > Sent: Thursday, May 24, 2012 11:00 PM > Subject: [AUTOSOMAL-DNA] IBD and IBS Revisited :( > > Scattered through out the other chromosomes are small sets of matching > segments, most either with 1,2 and 3, or  2, 3 and 4. > Normally I would think these are mainly IBS, but in this case where I > have these specific 4 testers, and they share many of the smaller > segments, isn't there a good chance many/most of these smaller > 'matches' are also IBD?  There are several combinations of the 4 > matching Mister X, but no match ever includes #1 and #4 together. > >snip > melissa springer robards