Question about differing match results between my Mother & I; why the huge disparity?

[sjadelson]

Madman's calculations are a sum total of his experience, meaning his personal results. So how can you say he is wrong. I vote for him.

It's when he freely and copiously applies his personal experience to others as if it were scientific fact that it breaks down. When he's declaring brothers to be different levels of cousin to the same match, it's very difficult to take him seriously.

[Yaffa]

I think Madman is generally right as long as we're talking about phased results, but personal experience and science/statistical accuracy are two different things.

Being that you have AJ in your family you have bottle-necking. Even with phasing would this not present a problem on predicting closeness of some relative matches???? You stated you were 1/2 AJ and your brother full. Your brother's parents are probably related and it appears your bother on your AJ side seems to share more cm with your AJ matches than you and probably because his parents are related where you have only one parent that is AJ. I would think it would be a little easier for you to sort out cm and possible relative closeness prediction than your brother??? On top of it AJ in general missing a lot of paper to connect matches further back. Just like our problem with AI ancestors.

[NYMark]

You're right about the bottlenecking, and I should have been clearer. Phasing is unlikely to be as as helpful for AJ folks as it is for non-Jews. I understand that Ancestry is phasing results but not making adjustments for endogamy. As a result, I have around 250 projected 4th-6th cousins, all but a couple of whom are AJ and most (maybe all) of whom are probably not that closely related.

I had my results phased against my half-brother's. On Gedmatch, I have 4 paternal matches of >.7 cM on the phased portion of the genome; he has well over 100. His parents do share a good deal of DNA.

So yes, it has been a lot easier to sort out for me, and the fact that he's not receiving the adjustment complicates things even further on that side.

Where the problem on his side is excess - hundreds of "2nd cousins", the challenge on mine is scarcity, probably because of recent European origin. The challenge is complicated by the cap on 23andMe and by the really lousy ethnicity estimate, absence of an AJ adjustment, and lack of a way to compare segments on Ancestry. Overall, despite my comments about FTDNA's excessively optimistic relationship projections and counting of tiny segments, this site and Gedmatch have been by far the most useful.

We're fortunate to have a pretty good paper trail on the maternal side, back to 5th great-grandfather on one line and all but two of my 3rd g-greats. It's one way I can be reasonably confident that the adjustment is often insufficient.

Being that you have AJ in your family you have bottle-necking. Even with phasing would this not present a problem on predicting closeness of some relative matches???? You stated you were 1/2 AJ and your brother full. Your brother's parents are probably related and it appears your bother on your AJ side seems to share more cm with your AJ matches than you and probably because his parents are related where you have only one parent that is AJ. I would think it would be a little easier for you to sort out cm and possible relative closeness prediction than your brother??? On top of it AJ in general missing a lot of paper to connect matches further back. Just like our problem with AI ancestors.

[NYMark]

Just want to correct myself. It's not hundreds of "2nd cousins"; it's 77.

You're right about the bottlenecking, and I should have been clearer. Phasing is unlikely to be as as helpful for AJ folks as it is for non-Jews. I understand that Ancestry is phasing results but not making adjustments for endogamy. As a result, I have around 250 projected 4th-6th cousins, all but a couple of whom are AJ and most (maybe all) of whom are probably not that closely related.

I had my results phased against my half-brother's. On Gedmatch, I have 4 paternal matches of >.7 cM on the phased portion of the genome; he has well over 100. His parents do share a good deal of DNA.

So yes, it has been a lot easier to sort out for me, and the fact that he's not receiving the adjustment complicates things even further on that side.

Where the problem on his side is excess - hundreds of "2nd cousins", the challenge on mine is scarcity, probably because of recent European origin. The challenge is complicated by the cap on 23andMe and by the really lousy ethnicity estimate, absence of an AJ adjustment, and lack of a way to compare segments on Ancestry. Overall, despite my comments about FTDNA's excessively optimistic relationship projections and counting of tiny segments, this site and Gedmatch have been by far the most useful.

We're fortunate to have a pretty good paper trail on the maternal side, back to 5th great-grandfather on one line and all but two of my 3rd g-greats. It's one way I can be reasonably confident that the adjustment is often insufficient.

[Yaffa]

You're right about the bottlenecking, and I should have been clearer. Phasing is unlikely to be as as helpful for AJ folks as it is for non-Jews. I understand that Ancestry is phasing results but not making adjustments for endogamy. As a result, I have around 250 projected 4th-6th cousins, all but a couple of whom are AJ and most (maybe all) of whom are probably not that closely related.

I had my results phased against my half-brother's. On Gedmatch, I have 4 paternal matches of >.7 cM on the phased portion of the genome; he has well over 100. His parents do share a good deal of DNA.

So yes, it has been a lot easier to sort out for me, and the fact that he's not receiving the adjustment complicates things even further on that side.

Where the problem on his side is excess - hundreds of "2nd cousins", the challenge on mine is scarcity, probably because of recent European origin. The challenge is complicated by the cap on 23andMe and by the really lousy ethnicity estimate, absence of an AJ adjustment, and lack of a way to compare segments on Ancestry. Overall, despite my comments about FTDNA's excessively optimistic relationship projections and counting of tiny segments, this site and Gedmatch have been by far the most useful.

We're fortunate to have a pretty good paper trail on the maternal side, back to 5th great-grandfather on one line and all but two of my 3rd g-greats. It's one way I can be reasonably confident that the adjustment is often insufficient.

Bottle-necking also happens in non-Jews if someone's ancestors come from an isolated area with access to a very small gene pool. My point for making the comment is madman's assessments on how close or far a match is. maybe madman has no bottle-necking in their family but many do. Just like I posted on a previous page how somehow I have a person who matches both my mother and my father's side so I match more on DNA with this person than my mother or father's side does. This making my match to this person appear closer to me when in fact it's probably further back and I share more than one ancestor to appear closer related. Without phasing in general and having other people in your family test many of us would not know if we shared more than one ancestor so some matches may appear closer than they are. All the more reason not to assume your cm is accurate in predicting closeness.

PS your very lucky to get back to 5th greats and some 3rd greats on AJ. !!!

[madman]

Bottle-necking also happens in non-Jews if someone's ancestors come from an isolated area with access to a very small gene pool. My point for making the comment is madman's assessments on how close or far a match is. maybe madman has no bottle-necking in their family but many do. Just like I posted on a previous page how somehow I have a person who matches both my mother and my father's side so I match more on DNA with this person than my mother or father's side does. This making my match to this person appear closer to me when in fact it's probably further back and I share more than one ancestor to appear closer related. Without phasing in general and having other people in your family test many of us would not know if we shared more than one ancestor so some matches may appear closer than they are. All the more reason not to assume your cm is accurate in predicting closeness.

PS your very lucky to get back to 5th greats and some 3rd greats on AJ. !!!

It all depends on how well you know your family tree I have two second cousins that had kids and there kids have the same number range as there parents so they all show up as 2nd cousins which they are but if you didn't know of the intermarriage between family members you would probably be lost.

[Yaffa]

It all depends on how well you know your family tree I have two second cousins that had kids and there kids have the same number range as there parents so they all show up as 2nd cousins which they are but if you didn't know of the intermarriage between family members you would probably be lost.

Thats not true I have met many people who thought they knew their family and then OOPs you have an NPE more common than people think. They also find out there are cousin matches they did not know about. Anyway my uncle just got a match at ancestry predicted 5-8th cousin but they are 3rd cousin once removed. I suspect they just share less DNA than what the charts say 3rd cousins should share.

[madman]

Thats not true I have met many people who thought they knew their family and then OOPs you have an NPE more common than people think. They also find out there are cousin matches they did not know about. Anyway my uncle just got a match at ancestry predicted 5-8th cousin but they are 3rd cousin once removed. I suspect they just share less DNA than what the charts say 3rd cousins should share.

whats not true?

OOPs you have an NPE

I never said anything about a NPE and I don't have any but if you don't know all your family secrets then sure you could easily have a NPE thats were DNA comes in.

They also find out there are cousin matches they did not know about.

It all depends on how well you know your family tree

3rd cousin once removed

Are you sure its not a half 3rd cousin once removed that would put it at a 5th cousin, or a 3rd cousin twice removed.

[blejerh]

I am also 1/2 AJ and my son is 3/4 AJ. I have whined on this forum before about how FTDNA's algorithm, which is biased towards total shared DNA, results in bizarre results for our family's matches.

My son has a larger total shared DNA with his AJ matches and often due to the algorithm and threshhold, our shared matches show up in his Matches, but not in mine. At one point my third cousin matched my son, but not me. Since Build 37 he doesn't match either of us LOL.

How do I know this? When I go to Gedmatch, I discover that a match that shows up only in his matches also is a match for me and that my son and my longest segment with that match is either identical or mine is longer.

Since there are so many of us in this boat, it would be good if the algorithm took this into account.

[Yaffa]

whats not true?



I never said anything about a NPE and I don't have any but if you don't know all your family secrets then sure you could easily have a NPE thats were DNA comes in.



It all depends on how well you know your family tree



Are you sure its not a half 3rd cousin once removed that would put it at a 5th cousin, or a 3rd cousin twice removed.

Autosomal is not going to pin an unk NPE further back on the tree. There is no paternity for deceased people back there on the tree. Y DNA cant prove paternity only possible male line and if there is a female NPE back there good luck.

And yes I am positive they are not a 1/2 3rd cousin once removed. They are 3rd cousin once removed.