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  #11  
Old 22nd June 2017, 10:27 AM
georgian1950 georgian1950 is offline
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Originally Posted by T E Peterman View Post
As I continue to study this, I'm finding that in all or most cases, I share more centimorgans with the match than the match shares with my paternal relative. This tells me that in these cases, I am related on both paternal & maternal sides, with the shared segment coming from the paternal side.

Timothy Peterman
You are exactly right. I have found that most parents are related within the last 300 years, even in cases where it appears that there is no way.

Since your mother died before she could be tested, we don't know in which cases she may have had a "match" too according to our arbitrary matching methodology, but undoubtedly she had enough DNA from the common ancestor to push the size of your match to larger than your father's.

Jack Wyatt (T787998)
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  #12  
Old 22nd June 2017, 02:04 PM
T E Peterman T E Peterman is offline
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As I see it, between my maternal uncle, my maternal aunt & myself, we have recovered roughly 81.25% of my maternal grandparents combined genomes, so even though my mother has no results in the database, I have good data on my maternal side.

Ann, I am using the default at Genome Mate Pro, which discards all segments under 7 centimorgans. A lot of folks might not ponder this, but a 5 cms segment could have originated as far back as 20 generations ago, so they should truly be ignored.

I was trying to think through the odd anomaly where I will share exact segments that are anywhere from 7.7 cms to over 10 cms with my paternal next of kin, but not with my father. I think I have a satisfactory answer now -lots of little, ignorable segments from my mother's side that push my centimorgan count above the threshhold, which my father of course, lacks.

Timothy Peterman
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  #13  
Old 22nd June 2017, 09:29 PM
prairielad prairielad is offline
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Quote:
Originally Posted by T E Peterman View Post
As I see it, between my maternal uncle, my maternal aunt & myself, we have recovered roughly 81.25% of my maternal grandparents combined genomes, so even though my mother has no results in the database, I have good data on my maternal side.

Ann, I am using the default at Genome Mate Pro, which discards all segments under 7 centimorgans. A lot of folks might not ponder this, but a 5 cms segment could have originated as far back as 20 generations ago, so they should truly be ignored.

I was trying to think through the odd anomaly where I will share exact segments that are anywhere from 7.7 cms to over 10 cms with my paternal next of kin, but not with my father. I think I have a satisfactory answer now -lots of little, ignorable segments from my mother's side that push my centimorgan count above the threshhold, which my father of course, lacks.

Timothy Peterman
The only way to truly say these matches do not match your father along these segments (unless they are also matching your maternal aunt or uncle) is to compare the Raw Data of your father and these matches without the matching thresholds that most companies impose. This is why many people suggest comparing at Gedmatch (requires you and match to upload) as Gedmatch allows one to adjust criteria to see if these segments are present

or you and match share Raw Data for chromosome/segment in question with each other and manually compare or use David Pikes utilities to compare

I for example have many matches at FTDNA that do not show up on either of my parents tests, these matches that utilize Gedmatch show that these longest segments (between 7cm and 9cM) almost always show up in one of my parent or the other.

Last edited by prairielad; 22nd June 2017 at 09:33 PM.
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  #14  
Old 23rd June 2017, 12:59 AM
T E Peterman T E Peterman is offline
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Many of my kits have been in gedmatch for a couple of years, including those relevant here. None of the anomalous matches are, though. I want to categorize matches correctly, but I seriously doubt that I will ever worry about those who only share 7 to 10 centimorgans.

My main objective is to identify portals that go back in time, reflecting a line of descent. Looking at the data for multiple kits in Genome Mate Pro, it is amazing what one can see. I group people by the narrowest side of family I can resolve them to. In many cases, this means to a particular great grandparent or even g-g grandparent. Once I assign matches to groups & look at those matching a single great grandparent across the 22 autosomal chromosomes, one can see additional clusters appearing & in many cases they center around ancestors as far back as 4th great, 5th great, or even 6th great grandparents. Everyone in such a cluster is related through that line of descent.

The following website explains more about my project:

https://www.familytreedna.com/groups...-timothy/about

Timothy Peterman
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  #15  
Old 23rd June 2017, 05:44 AM
Ann Turner Ann Turner is offline
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Quote:
Originally Posted by T E Peterman View Post
I was trying to think through the odd anomaly where I will share exact segments that are anywhere from 7.7 cms to over 10 cms with my paternal next of kin, but not with my father. I think I have a satisfactory answer now -lots of little, ignorable segments from my mother's side that push my centimorgan count above the threshhold, which my father of course, lacks.

Timothy Peterman
A very high percentage of those small segments will not be from your mother's side. Rather, they are pseudo-segments, a hodge-podge of alleles from your mother and your father.

http://segmentology.org/2015/10/02/a...n-ibs-segment/
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  #16  
Old 23rd June 2017, 07:18 AM
T E Peterman T E Peterman is offline
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Of course...

As I see it, a 1 cm segment may have originated as far back as 100 generations ago. A 2 cm segment may have originated as far back as 50 generations ago. These are just scattered across the population like dust in the wind.

That is why I am only interested in segments greater than 7 cms which are shared with a match exactly by 2 or more participants in my project.

In cases where a paternal uncle of mine & I share a match, but my father doesn't, I have to say that the majority of those tiny segments to be ignored come from my mother's side. If my father had a majority, he would share the match...

One thing that I wish Family Tree DNA would do. In cases where siblingship is both claimed by the participants & both share the expected centimorgan count, Family Tree DNA would report match data & show centimorgans for both, even if only one of the siblings met Family Tree DNA's matching criteria for the match.

Timothy Peterman
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  #17  
Old 23rd June 2017, 09:52 AM
georgian1950 georgian1950 is offline
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Quote:
Originally Posted by Ann Turner View Post
A very high percentage of those small segments will not be from your mother's side. Rather, they are pseudo-segments, a hodge-podge of alleles from your mother and your father.

http://segmentology.org/2015/10/02/a...n-ibs-segment/
Ann, how would the results of your study be affected if the greater majority of us share one common male ancestor about 300 years ago?

Jack Wyatt
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