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

[Yaffa]

Actually I had it right two 4th cousins who had kids would have same amount of dna as a 4th cousin.



now Yaffa has a 4th cousin and a 5th cousin who had a kid and calling it a 3rd cousin thats impossible it would be a 4.5 cousin and still register at the high end of a 5th cousin with dna.

No thats not what I have. Your not understanding. The more ancestors you share in common the more you will be genetically related.

And about how you predicting DNA matches. I have a 35 cm match and so does my great uncle. He has that same match at about 35 cm. He is 2 generations closer to this match than I would be on paper. You know what this means? More than likely my grandmother got more of that DNA from our ancestor than my grandmother's brother did. Every person gets different DNA from their ancestors in different amounts. I have other matches in my family where one of us shares more cm with a match than the other.

[madman]

No thats not what I have. Your not understanding. The more ancestors you share in common the more you will be genetically related.

And about how you predicting DNA matches. I have a 35 cm match and so does my great uncle. He has that same match at about 35 cm. He is 2 generations closer to this match than I would be on paper. You know what this means? More than likely my grandmother got more of that DNA from our ancestor than my grandmother's brother did. Every person gets different DNA from their ancestors in different amounts. I have other matches in my family where one of us shares more cm with a match than the other.

theres two ways to explain this 35cm match which would be a 6th cousin.

1. this is a random match and isn't related.
or
2. your grandmother and your great uncle are half siblings and there parents are related differently to the person in question.

for an example

you 35cm
parent 70cm
grandparent 140cm
great grandparent 280cm -----------same generation
-----------------------------
great uncle 35cm
parent 70cm -----------same generation
-----------------------------
that would mean your great grandparent would have 280cm and his parent would have 70cm

[Yaffa]

theres two ways to explain this 35cm match which would be a 6th cousin.

1. this is a random match and isn't related.
or
2. your grandmother and your great uncle are half siblings and there parents are related differently to the person in question.

for an example

you 35cm
parent 70cm
grandparent 140cm
great grandparent 280cm -----------same generation
-----------------------------
great uncle 35cm
parent 70cm -----------same generation
-----------------------------
that would mean your great grandparent would have 280cm and his parent would have 70cm

Grandma is not a 1/2 sibling. This is my direct mother line. This match my uncle and I share is on his father's side (my Great Grandfather, my grandmother's father) .. This match we have also matches other cousins on my great grandfather's side. None of us lost this match after build 37. There are also other reasons we know this match is accurate even though we can't connect paper.

[NYMark]

Here are some comparative results from the top matches I share with my fully Ashkenazi half-brother, listed by total cM. As I've indicated, I'm half AJ.

All matches are predicted 2nd cousins for him. Order is based on his Family Finder.

Match 1 Him: Total cM 200.23 Longest Block 9.94

Match 1 Me: Total cM 125.03 Longest Block 7.23 (Projected 4th)

Match 2 Him: Total cM 155.68 Longest Block 16.56

Match 2 Me: Total cM 91.86 Longest Block 21.91 (Projected 3rd)

Matches 3 and 4 on his list don't match me. In one of these two cases, the longest segment is only 7 cM and the total shared is 152.99.

Match 5 Him: Total cM 150.55 Longest Block 9.66

Match 5 Me: Total cM 118.58 Longest Block 9.66 (Projected 5th-Remote)

Needless to say, at around this level, I have some matches that are not in common with him, but the pattern is generally, and as would be expected, one of his having a significantly higher total shared when we have a common match.

This also might be illuminating. Matches of mine from a single family.

Grandmother (1/2 AJ) Total Shared 40.01 Longest Block 9.33

Daughter 1 (3/4 AJ) Total Shared 72.19 Longest Block 15.34

Daughter 2 (1/4 AJ) Total Shared 35.44 Longest Block 8.77

Granddaughter (3/8 AJ?) Total Shared 50.23 Longest Block 15.10
(Daughter 1 is her mom)

If I take under 5 cM segments into account, the granddaughter shares 21.75 cM with me – over 40% of the total – that she doesn't share with any of the other relatives (the longest block is 3.94.) Daughter 2 shares 7.79 cM with me – over 20% of the total – but not with her mother or her sister. Blocks are between 1 and 2.67 cM. I don't think this has any genealogical meaning, but it points to the perils both of assuming that total cM is valid as a sole criterion and of relying on the projections, both adjusted and unadjusted, especially with unphased data and in endogamous populations.

[Yaffa]

@madman --I have another interesting match where I share a match to the same living person (Ill call him John) on both my father's Mother's side and mother's side.

My 1/2 sister (Father's side) matches John as 4th Cousin - Remote Cousin cm 37.52 block 11.96

My uncle (mom's side matches) John as 4th Cousin - Remote Cousin - cm 42.75 block 10.04

I match John as 4th Cousin - Remote Cousin - cm 49.35 block 11.47

My sister on my father's side does not match my uncle on my mother's side at all.

First off my father and mother are not related that anyone knows of.....Per chrome browser I did no doubt get DNA from both my mother's and father's side to match John at a higher CM level than my great uncle who would be on paper closer to this ancestor than I would.

Second, I have no doubt this match is accurate even though on paper I have no proof of being related to John. We have several NPE in the family. My mother's family lived in the same town as John and we lived on his land. John's family were land speculators. Johns family also known for marrying in the Cherokee nation. In general my mother's family does have matches to the Cherokee nation and people who have documentation of being on the trail of tears. My father's mother's mother was also Cherokee and why my father's side probably also matches John. We have other matches on my father's mother's mother's side who has surnames who are connected to John's surname.

So with all that tell me madman if I was not able to phase my DNA matches how you could possibly predict why I got more DNA from a match we all share?? Not only that I or you can not predict where and when I am related to John because I might share more than one ancestor with him on two completely different sides of my family.

[madman]

Match 1 Him: Total cM 200.23 Longest Block 9.94

Match 1 Me: Total cM 125.03 Longest Block 7.23 (Projected 4th)

Match 2 Him: Total cM 155.68 Longest Block 16.56

Match 2 Me: Total cM 91.86 Longest Block 21.91 (Projected 3rd)

Matches 3 and 4 on his list don't match me. In one of these two cases, the longest segment is only 7 cM and the total shared is 152.99.

Match 5 Him: Total cM 150.55 Longest Block 9.66

Match 5 Me: Total cM 118.58 Longest Block 9.66 (Projected 5th-Remote)

Needless to say, at around this level, I have some matches that are not in common with him, but the pattern is generally, and as would be expected, one of his having a significantly higher total shared when we have a common match.

This also might be illuminating. Matches of mine from a single family.

Grandmother (1/2 AJ) Total Shared 40.01 Longest Block 9.33

Daughter 1 (3/4 AJ) Total Shared 72.19 Longest Block 15.34

Daughter 2 (1/4 AJ) Total Shared 35.44 Longest Block 8.77

Granddaughter (3/8 AJ?) Total Shared 50.23 Longest Block 15.10
(Daughter 1 is her mom)

200.23cm = 3rd Cousin
125.03cm = 4th Cousin
155.68cm = 4th Cousin
91.86cm = 4th Cousin
152.99cm = 4th Cousin
150.55cm = 4th Cousin
118.58cm = 4th Cousin
40.01cm = 5th Cousin
72.19cm = 5th Cousin
35.44cm = 6th Cousin
50.23cm = 5th Cousin

[NYMark]

So, I'm a "4th Cousin" to someone who's a "3rd Cousin" to my half-brother.

And I'm a "5th cousin" to three generations of people: a mother (probably closest to me in age), her daughter, and her granddaughter, and a "6th Cousin" to another daughter who is a generation closer to me than the granddaughter and purported "5th Cousin."

Makes a whole lot of sense. . .

200.23cm = 3rd Cousin
125.03cm = 4th Cousin
155.68cm = 4th Cousin
91.86cm = 4th Cousin
152.99cm = 4th Cousin
150.55cm = 4th Cousin
118.58cm = 4th Cousin
40.01cm = 5th Cousin
72.19cm = 5th Cousin
35.44cm = 6th Cousin
50.23cm = 5th Cousin

[madman]

both adjusted and unadjusted, especially with unphased data and in endogamous populations.

so your saying your not phasing your matches I would only count a minimum of 7-8cm segments if your counting any amount below that your just asking for false positives.

[NYMark]

There ya go. . .We may not disagree after all. I can only phase against a half-sib. No parents available to test.

FTDNA doesn't phase. Only Ancestry does at present, but they aren't releasing the matching info. My brother's results have disappeared from Gedmatch, and I have a grand total of four matches with over 7 cM on phased results.

A huge amount of this would go away with phasing, which is why i've been going off on FTDNA for counting segments of under 5 cM. 7 is probably a better threshold.

Not sure that 7-8 on AJ is all that significant even when phased.

Counting only 7-8 cM segments, that ~125 cM fourth cousin has a total of 7.23.

so your saying your not phasing your matches I would only count a minimum of 7-8cm segments if your counting any amount below that your just asking for false positives.

[mollyblum]

Guys and (women)-
1. You are arguing with someone who calls himself "madman."

2. FtDNA, Ancestry, 23 & me, etc and the best scientist and specialists cannot narrow down the precision of generational ancestry (aside from parent to child and extremely close relationships) but apparently "madman" has it all worked out on a spreadsheet easy as pie.

3. C'mon!

So, I'm a "4th Cousin" to someone who's a "3rd Cousin" to my half-brother.

And I'm a "5th cousin" to three generations of people: a mother (probably closest to me in age), her daughter, and her granddaughter, and a "6th Cousin" to another daughter who is a generation closer to me than the granddaughter and purported "5th Cousin."

Makes a whole lot of sense. . .

[NYMark]

Not so sure, with phasing, his numbers are probably pretty good but still not universally accurate.

I was thinking troll until the most recent post. . .

Guys and (women)-
1. You are arguing with someone who calls himself "madman."

2. FtDNA, Ancestry, 23 & me, etc and the best scientist and specialists cannot narrow down the precision of generational ancestry (aside from parent to child and extremely close relationships) but apparently "madman" has it all worked out on a spreadsheet easy as pie.

3. C'mon!

[madman]

There ya go. . .We may not disagree after all. I can only phase against a half-sib. No parents available to test.

FTDNA doesn't phase. Only Ancestry does at present, but they aren't releasing the matching info. My brother's results have disappeared from Gedmatch, and I have a grand total of four matches with over 7 cM on phased results.

A huge amount of this would go away with phasing, which is why i've been going off on FTDNA for counting segments of under 5 cM. 7 is probably a better threshold.

Not sure that 7-8 on AJ is all that significant even when phased.

Counting only 7-8 cM segments, that ~125 cM fourth cousin has a total of 7.23.

using less then 5cm will match to just about any random person in the world they need to at least have 5-6cm as the minimum but then you would have people complaining because there thousands of matches are now just a handful.

[NYMark]

Agreed 100%. That's been my point all along.

using less then 5cm will match to just about any random person in the world they need to at least have 5-6cm as the minimum but then you would have people complaining because there thousands of matches are now just a handful.

[Biblioteque]

Vote for Madman

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.

[NYMark]

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.

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.