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  #1  
Old 6th June 2017, 06:37 AM
Lucky Lucky is offline
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Phasing

I have two questions about the maternal and paternal phasing on family finder.

Firstly, when will this be extended to include phasing against people further out on the tree than 3rd cousins?

Secondly I recently received matches from two siblings who match me at the same point for a segment of 13.13cMs. One of the siblings appears with a maternal symbol beside him and the other one doesn't. Why would this be? My overall match with the phased person is 41cMs in total, other is 39cMs, could the overall match size be the reason?
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  #2  
Old 6th June 2017, 12:04 PM
Ann Turner Ann Turner is offline
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Does it look like the other party has linked both siblings to their tree(s)?
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  #3  
Old 11th June 2017, 03:25 PM
Lucky Lucky is offline
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Yes, once one of the people has added a tree to their account and they are indeed linked as brother and sister.

Why has only one of these phased maternal?
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  #4  
Old 11th June 2017, 04:50 PM
ltd-jean-pull ltd-jean-pull is offline
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I'm guessing here but I think there would be too much potential for mistakes if it was extended past third cousins, particularly in endogamous populations.

I do understand your frustration because the best match for one of the kits I manage is a 3C1R. I can't be certain that all the matching segments are from the line we know of because our ancestor (gt-grandfather of my person who tested) emigrated from this smallish Scottish town in the 1850s whereas their ancestor stayed and married within the local community for a couple more generations. Everyone seemed to be cousins to everyone else in this town. OK - that's an exaggeration, but there was a lot of intermarriage, plus, according to church records, our gt-grandfather's uncle had a few children "born in uncleanness" and they're just the ones we know of.

I hope the father of the 3C1R will test.
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  #5  
Old 12th June 2017, 09:27 AM
Ann Turner Ann Turner is offline
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Quote:
Originally Posted by Lucky View Post
Yes, once one of the people has added a tree to their account and they are indeed linked as brother and sister.

Why has only one of these phased maternal?
In that case, I'm out of ideas. There must be some mysterious additional criteria that one sibling meets and the other one doesn't.
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  #6  
Old 15th June 2017, 09:14 AM
Lucky Lucky is offline
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Thanks for the reponses. I thought maybe there was a total CM size threshold to be met before phasing happened however as phasing should be based on segments I don't know what is going on here.

With the same account I am having another problem with phasing. Whilst most of my phasing is correct, two maternal uncles don't phase as 'purple' as they should. I phase as red on one of their accounts and as blue on the other's accounts - they are full siblings and I have a full nephew/uncle match with both of them. I have proven matches through both my grandparents so there is no doubt whatsoever that I'm not related to both of them.

I suspect there may be a wider problem with phasing as the process has not been rolled out as originally intended and there seems to be anomolies such as what I have described that have not been fixed.
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  #7  
Old 15th June 2017, 11:02 AM
prairielad prairielad is offline
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Quote:
Originally Posted by Lucky View Post
Thanks for the reponses. I thought maybe there was a total CM size threshold to be met before phasing happened however as phasing should be based on segments I don't know what is going on here.

With the same account I am having another problem with phasing. Whilst most of my phasing is correct, two maternal uncles don't phase as 'purple' as they should. I phase as red on one of their accounts and as blue on the other's accounts - they are full siblings and I have a full nephew/uncle match with both of them. I have proven matches through both my grandparents so there is no doubt whatsoever that I'm not related to both of them.

I suspect there may be a wider problem with phasing as the process has not been rolled out as originally intended and there seems to be anomolies such as what I have described that have not been fixed.
You have to share one of their matches that are linked to their maternal side, and one of their matches that are linked to their paternal side to show up as Both (purple) on their accounts.

phasing only looks at shared DNA segments between two linked people and the matches which share that same segment.

For example,
Where you show as Red on maternal Uncle, of all the matches you share and share an overlapping segment with your uncle, only one or more of those matches match your uncles phased maternal, none of the shared matches which match you and uncle on overlapping segments must not match up to phased paternal side.

Until there are linked matches that span the whole sections that you share with uncle(s), you do not know which side of his family you are matching him along that segment you share with him. You maybe sharing DNA from either side. Phasing can not identify until he has a link maternal or paternal match which covers that segment of DNA

Last edited by prairielad; 15th June 2017 at 11:06 AM.
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  #8  
Old 15th June 2017, 07:24 PM
Lucky Lucky is offline
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The lack of purple phasing I am referring to is on my two uncles accounts not on mine where they simply appear as maternal (to me).

I match one of my uncles maternal 1st cousins and one of my uncles paternal 1st cousins for matches of 422cMs and 415cMs (my 1st cousins 1R) therefore I can see I do have enough segments to phase properly through both of my maternal grandparents. Both of my uncles match both of these people and other proven relations also related on both sides of the family so that is why I can't understand why the phasing isn't correct.

Plus if there was a problem it shouldn't be phasing me maternal only on one account and paternal only on the other. I imagine there must be something wrong in the phasing algorithm.

Three of my cousins who share less DNA with the same two uncles phase purple.

Another thought - my test was done the earliest (in 2012) - could this be an issue? Could my results be recorded/measured slightly differently perhaps because a different system was used in those days?
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  #9  
Old 15th June 2017, 08:23 PM
prairielad prairielad is offline
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I was referring to your uncles accounts, if not clear.
It does not matter how much DNA is shared, it depends on which segments in each uncle have been identified as maternal or paternal. You will only be placed based on if and how you share these identified segments.

You have to match each one separately with an in common with match(that shares same segment) that has been identified as maternal and and another one identified as paternal (sharing same segment). If you only share a maternal match (Uncles maternal match with same segment), then you will be assigned on his maternal tab, if you do not share a match with him that was identified as paternal, you will not show up in both tab (even though you know you share both his lines).
Sibling are not phased with one another as they share both line, need 3rd match to determine maternal vs paternal.
Anyone below ones line(descendants ie children, niece/newphew, grandchildren, ect) that share both your maternal and paternal lines can not be phased/identified unless they share a match that is linked strictly to your maternal or paternal line, or share a maternal match and a paternal match (same segment in all of you)

Phasing deals with matching segments that can be identified as maternal and paternal.
Even though one uncle list you as maternal and the other paternal, phasing will not look at them together as siblings and assume that you should then show up on their both tab.
You will have to share a segment deemed paternal with the one uncle(uncle that has you as maternal) and share a segment deemed maternal with the other uncle (uncle that has you as paternal) before you show up on their both tab.

Last edited by prairielad; 15th June 2017 at 08:29 PM.
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  #10  
Old 18th June 2017, 04:46 PM
Lucky Lucky is offline
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Thanks for your clear reply but I understand all of that.

I didn't make this clear in my last posts but I share many segments with both my uncles on both their maternal and paternal side - I have strong matches to their paternal and maternal cousins and also match a variety of 2nd, 3rd and 4th cousins who share specific blocks of DNA in common with me and my uncles.

As I said 3 of my other cousins share the same matches with others and all of them phase purple however I don't.

I have read on here in the poast that others seem to have the same phasing problem as I do. I think there must be a fault somewhere which might explain why phasing hasn't been rolled out as initially announced.
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