Genetic Distance of 0 @ 25, 2 @ 67, but 8 @ 111??

[CJohnson]

Is this common? I have another match that's a 0 genetic distance at 25 markers, 1 at 67, but 6 at 111!

I upgraded from a 67 marker test to the 111 because I had so many surnames that don't match mine, including my closest match (Mills!) I know that having a really common surname such as mine (Johnson) can be problematic but how common is it to have an exact 67 marker match (gen. dist. 0) with a different surname?

I only have 2 matches that have done the 111 test so until more have (& hopefully add a gedcom or at least most distant ancestor info) it hasn't been much help.

The "Tip" calculator for the exact match at 67 with the Mills surname gives a probability of 90% for a common ancestor within 4 generations. 90% sounds pretty darn sure. BUT the match that was a 0 distance at 25 markers, 1 at 67 and jumped to 6 at 111 gave the probability of 71% for a mrca within 4 generations when comparing 67 markers, but now when comparing 111 markers that number has dropped to 5%!

From 71% at 67 to 5% at 111??

Now I'm left wondering just how close that Mills match really is? Obviously, not a 90% probability of a mrca in 4 gens.

I just want some input and opinions on what to make of this, how common is this, etc.

Thanks!

PS. Yes, I'm aware of the ability to change the number of generations in the Tip calculator that a match & I don't share a mrca but unfortunately, I don't know for sure what that number is.

[dna]

As you had observed, predictions can change when changing the number of markers tested.

With the increased number of markers tested, the quality of the guess keeps improving.

I am a hobbyist with no degree in genetics, so the following would be a rough comparison and not a precise explanation.

With markers it is a little bit like with the opinion polls. If you ask more markers (people) you are more sure about the result obtained, even if in all the cases the answer was, let's say, 90%.

If your match shared any information about himself, you can probably estimate the number of generations, to be used in the TiP calculator, him and you don't share. However, before you start estimating, try to input some values that are meaningful to you, and see how the results change... https://www.familytreedna.com/learn/...bility-change/

The Family Tree DNA Learning Center has some tidbits about TiP. Enter TiP into the search box.

P.S. Adoptions and false paternity are not the only ways one can get a family name that is different from the family name of his father at birth. But that is non-genetic genealogy

[1798]

Is this common? I have another match that's a 0 genetic distance at 25 markers, 1 at 67, but 6 at 111!

I upgraded from a 67 marker test to the 111 because I had so many surnames that don't match mine, including my closest match (Mills!) I know that having a really common surname such as mine (Johnson) can be problematic but how common is it to have an exact 67 marker match (gen. dist. 0) with a different surname?

I only have 2 matches that have done the 111 test so until more have (& hopefully add a gedcom or at least most distant ancestor info) it hasn't been much help.

The "Tip" calculator for the exact match at 67 with the Mills surname gives a probability of 90% for a common ancestor within 4 generations. 90% sounds pretty darn sure. BUT the match that was a 0 distance at 25 markers, 1 at 67 and jumped to 6 at 111 gave the probability of 71% for a mrca within 4 generations when comparing 67 markers, but now when comparing 111 markers that number has dropped to 5%!

From 71% at 67 to 5% at 111??

Now I'm left wondering just how close that Mills match really is? Obviously, not a 90% probability of a mrca in 4 gens.

I just want some input and opinions on what to make of this, how common is this, etc.

Thanks!

PS. Yes, I'm aware of the ability to change the number of generations in the Tip calculator that a match & I don't share a mrca but unfortunately, I don't know for sure what that number is.

A GD of 8 at 111 markers could be 1200 years. Each marker difference could be an indication of a SNP. Depending on the mutation rate in your Y-Line each SNP could represent 100-200 years. Two friends who took the Big-Y tests and had a GD of 10 at 111 have 10 different SNPs to each other.

[lgmayka]

Is this common? I have another match that's a 0 genetic distance at 25 markers, 1 at 67, but 6 at 111!

On how many markers do you actually differ? One marker can experience a multi-step mutation--a single event--that FTDNA counts as multiple mutations.

A marker can drop as many as 5 steps in one event.

[1798]

On how many markers do you actually differ? One marker can experience a multi-step mutation--a single event--that FTDNA counts as multiple mutations.

A marker can drop as many as 5 steps in one event.

I think that in the near future that we will see testers with different SNPs who match at 111.

[Armando]

I think that in the near future that we will see testers with different SNPs who match at 111.

What does that have to do with his statement? He is pointing out that a jump from 1 GD at 67 to 6 GD at 111 could be caused by a multi-step mutation. That is an extremely good point and your comment doesn't invalidate that in any way.

[1798]

What does that have to do with his statement? He is pointing out that a jump from 1 GD at 67 to 6 GD at 111 could be caused by a multi-step mutation. That is an extremely good point and your comment doesn't invalidate that in any way.

So you think that a multi-step mutation will mean that he is more closely related. We are not closely related by YSTRs. We are related by SNPs. I am after finding a what I thought was a great match only to learn that he is not in the same SNP branch. So instead of being related within a genealogical time frame we have a TMRCA of perhaps around 4,500 years.

[CJohnson]

On the Match that's a GD of 6 at 111 there are 6 different markers with a one copy difference. I'm I-M253 (predicted by FTDNA, but considered certain by one of Ken Nordtvedt's calculators) and the match is I-Z138 (proven.)

Only one other person who has tested above 37 markers is in my family group in my surname project so I can't see the other match's STR results.

Something else I should have mentioned is I have a micro-satellite on DYS710. The value is 33.2 "normalized" to 33. In my surname project this value is listed as the min, max, & modal for my family group but how does this affect the accuracy for people not in my surname project?

I'm going to see if I can attach a table I made of 4 matches because the way the probabilities go up and down with the number of markers I feel like there should be some way I can narrow down the TMRCA, I just don't know how to go about it. Any help anyone could give me would be greatly appreciated!

[CJohnson]

Ok, here's the table of my closest matches at 67 markers.

[Armando]

So you think that a multi-step mutation will mean that he is more closely related. We are not closely related by YSTRs. We are related by SNPs. I am after finding a what I thought was a great match only to learn that he is not in the same SNP branch. So instead of being related within a genealogical time frame we have a TMRCA of perhaps around 4,500 years.

Yes, a multi-step mutation can mean they are more closely related.

Yes, SNP testing should be done along with STR testing to rule out spurious matches. Getting everyone to do SNP testing is the hard part and now that we know that there will be a Deep Clade 2.0 test then there is almost no sense in getting SNP testing done before it's release except in the event of a close match at 37, 67, or 111 markers with someone that has tested down to a terminal SNP. Then they can order that specific terminal SNP test.

[1798]

Yes, a multi-step mutation can mean they are more closely related.

Yes, SNP testing should be done along with STR testing to rule out spurious matches. Getting everyone to do SNP testing is the hard part and now that we know that there will be a Deep Clade 2.0 test then there is almost no sense in getting SNP testing done before it's release except in the event of a close match at 37, 67, or 111 markers with someone that has tested down to a terminal SNP. Then they can order that specific terminal SNP test.

I think that the mistake that some people make is that a lot of YSTR mutations are not permanent but SNPs are. That is the reason that two people who seem close are not in the same subgroup. P311 the man that we are descended from had only one haplotype.

[Armando]

I think that the mistake that some people make is that a lot of YSTR mutations are not permanent but SNPs are. That is the reason that two people who seem close are not in the same subgroup. P311 the man that we are descended from had only one haplotype.

Yes, I am sure that there are a lot of people that aren't aware that SNP markers are passed on through the generations without being lost while STRs change without evidence of previous markers. However, lgmayka has been well aware of that since he is a haplogroup admin and part of the ISOGG group.

Your specific situation isn't necessarily this person's situation.

[Armando]

On the Match that's a GD of 6 at 111 there are 6 different markers with a one copy difference. I'm I-M253 (predicted by FTDNA, but considered certain by one of Ken Nordtvedt's calculators) and the match is I-Z138 (proven.)

Only one other person who has tested above 37 markers is in my family group in my surname project so I can't see the other match's STR results.

Something else I should have mentioned is I have a micro-satellite on DYS710. The value is 33.2 "normalized" to 33. In my surname project this value is listed as the min, max, & modal for my family group but how does this affect the accuracy for people not in my surname project?

I'm going to see if I can attach a table I made of 4 matches because the way the probabilities go up and down with the number of markers I feel like there should be some way I can narrow down the TMRCA, I just don't know how to go about it. Any help anyone could give me would be greatly appreciated!

Ok, here's the table of my closest matches at 67 markers.

I-Z138 is a subclade of I-M253. You need to get tested for I-Z138 to determine of you are also positive for it. You should go ahead and order that test, if you haven't already, unless you are willing to get the Big Y and your matches have ordered the BigY. You would need to email them to find out if they have. You also need to see if the other people in the list of matches have had SNP tests. The Haplogroup I Y-DNA Project does not use surnames so I can't cross-reference the surnames in your spreadsheet. You should also join the Haplogroup I Y-DNA Project and email the admins for advice based on your markers and matches.

[owen]

two first cousins have 1 genetic distance at 12 markers, 2 at 37, 2 at 67, and 4 at 111. 3 STR markers different.

[1798]

two first cousins have 1 genetic distance at 12 markers, 2 at 37, 2 at 67, and 4 at 111. 3 STR markers different.

I also know strangers that have a GD of 4 at 111.