Concepts – Y DNA Matching and Connecting with your Paternal Ancestor

Recently, I received a question about exactly how and why we can use Y DNA to identify or connect with a patrilineal ancestor.

“I do not quite understand how the profiles can be identified specifically to an ancestor since that person is not among us to provide DNA material for “testing” and comparison.”

That’s a great question.

Let’s look at the answer in steps.

Males Inherit the Y Chromosome from Dad

First and foremost, and the most important part of using the Y chromosome for genetic genealogy is understanding that the Y chromosome is passed from father to son without any DNA being incorporated from the mother. So, in essence, the Y chromosome is passed intact.

In most western cultures, the surname is passed utilizing the same inheritance path, so the Y DNA and the surname are passed along together – hence Y DNA projects are often called surname projects. If the Y DNA is passed from father to son, without any unexpected nonpaternal events or adoptions in the mix, then the surname and the Y DNA will match since the advent of surnames in the culture where the original ancestor that adopted that surname was born.

Let’s look at England for example. Often people there adopted surnames after the Norman invasion (1066) and by the 1200s, most people had surnames.  Of course, there weren’t a lot of records for normal working-class people at that time, but by the time church and parish records started to be more reliably kept, in the 1580s, give or take, surnames were well established and everyone had one.  John who lived on the green was now John Green and John who lived by the brook was now John Brook.  Their sons took their surnames upon birth in a traditional marital relationship.

Y and mito

Therefore, the Y chromosome is passed from male to male, father to son, forever, illustrated by the blue squares in the pedigree chart above…with the Y DNA almost entirely intact.

Mutations Happen – Whenever

Did you catch that word, “almost?”

Yea, it’s a “gotcha” word, but it’s also why genetic genealogy works. If it weren’t for occasional mutations, all of the Y DNA would be exactly the same, and not at all useful for genealogy.  Thankfully, that’s not the case.

From time to time, a mutation occurs as the DNA is passed from father to son.  We see the results of this inheritance and mutation pattern in the DNA markers we test for genetic genealogy.

The markers we typically use for genetic genealogy are called STR, Short Tandem Repeat, markers. They are the 12 marker, 25, 37, 67 and 111 marker panels tested by Family Tree DNA.

These types of markers mutate more rapidly than the other type of Y DNA markers typically used to determine haplogroups, known as SNPs, Single Nucleotide Polymorphisms.

STRs and SNPs

There are two primary differences between STRs and SNPS relative to genealogy.

The first difference is that STR mutations are what I call stutter or repeat mutations. Think of a copy machine that got stuck.  Let’s say your DNA at a location, meaning at a specific marker, looks like this: “TAGA.”  However, when the copying of that DNA for the next generation was done, 20 or 30 or 40 generations ago, long ago in a faraway place, the copy mechanism got stuck and now you have 5 “TAGA”s in a row, so “TAGATAGATAGATAGATAGA.”  Now you have a value of 5 instead of a value of 1 in that marker location.

SNP mutations, on the other hand, occur at one location and are defined by one of the nucleotides, T, A, C or G that live in that location getting swapped for a different nucleotide. So, now, at that particular address, T becomes C.  That’s a single nucleotide polymorphism and those changes are how haplogroups and their branches are formed.  If you are interested, you can read more about haplogroups and how they are born here.

In addition to switches between nucleotides, you can also have insertions of DNA and deletions of all DNA where the value becomes 0, but for now, let’s leave it at STRs and SNPs. I wrote a detailed article about SNPs and STRs here.

Oh yes, and as one final bad joke, the mutations, occasionally, revert back – that’s called a back mutation. I know, it’s a really bad joke, meant, I’m sure to confound genetic genealogists.  And the only way you’re ever going to discover a back mutation is through known genealogy when you see it occur in a line.  Just remember, mutations can happen anytime they want to – on any marker – in either direction – and sometimes in increments of more than 1.  So, a marker value can go from 10 to 12 in one event, for example.

Some STR markers are more prone to mutations than others, and those are known as slow or fast moving markers.

STR fast and slow

The project pages color code each marker in the column header as to its known characteristics relative to mutation speed.

STR color legend

The legend above, from the Family Tree DNA Learning Center provides the color coding for the column header values.  Fast in any group = red.

The second difference between STRs and SNPs is that STR mutations happen more frequently than SNP mutations, making them useful in a genealogically relevant timeframe, where SNPs happen much less frequently, and are therefore utilized to determine and identify haplogroups and haplogroup branches, meaning deeper genealogy, generally before the adoption of surnames.

Having just said that, the timeframe of SNPs and STRs is beginning to overlap, but STRs are still the gold standard of genealogy testing to compare men born within the past few hundred years, especially with a common surname.

In genealogy testing, you always start with STR testing and then progress to SNP testing, if you wish.

Marker Comparisons

So, let’s take a look at how STR marker comparisons work in a hypothetical example.

Let’s say, for example, that we have 6 sons of Abraham Estes who died in 1712. Descendants of those sons have tested their Y DNA and sure enough, they have some mutation differences between them.  This would be expected in the 7-9 generations between when Abraham lived and the current generation testing.

Let’s say that all 6 of Abraham’s sons matched his STR markers exactly back then, but in the 7-9 generations between Abraham and the present day testers, one mutation has occurred in each of 4 lines on a different marker. Two of his son’s lines have not had any mutations at all.

Of course, we don’t know this before we evaluate the DNA. It’s the marker values themselves that will inform us about Abraham’s DNA.

STR mismatch example

In our example, Abraham’s six sons’ lines tested, as shown above. All of their markers match each other, except one marker in each of 4 mens’ tests, highlighted in yellow above.

How do we know those are mutations? Because the majority of the results from the other sons lines are all the same.  Therefore, we can utilize the DNA of the 6 different son’s lines to determine the DNA of Abraham at each one of those different marker locations.  So, let’s reconstruct Abraham’s values for these markers.  Isn’t this fun!!!

STR Abraham reconstruction

The green row at the bottom is reconstructed Abraham. We know the value of each marker based on the common values of his sons’ lines.  The only place the sons and their descendants could have gotten that DNA was from Abraham, the common ancestor of all of these 6 men.

So, with marker 393, all 6 sons lines have a value of 13, so Abraham had to have a value of 13 as well.

On marker 19 (394), all the different sons lines, except one, Elisha, had a value of 14, so Abraham’s value was 14 and Elisha’s line in a generation someplace between Abraham and the current tester has developed the mutated value of 13.

Line Marker Mutations

It’s possible that some of these markers are known as or can function as “line marker” mutations – identifying specific son’s lines. Let’s say, for example, that a mutation occurred between Abraham and Moses at location 426 such that Moses has a value of 11.  That means that every one of Moses’s sons would have had a value of 11 at 426, as opposed to the value of 12 present in Abraham’s other sons at that marker.  Therefore, if someone tests who doesn’t know which of Abraham’s son they descend from, and they have a value of 11 at 426, I’d start by looking at Moses.  That isn’t to say that same mutation couldn’t have happened in another line too, but Moses is still a good place to begin since we know his line has 11 at 426.

Of course the only way to learn that information about Moses, positively, is to find men who descend from each of his sons and recreate Moses in the same way we recreated Abraham.

What About False Paternity?

Let’s say that an Estes male who had an undocumented adoption occur 3 or 4 generations upstream in his Estes line tests – and he is entirely unaware that an “adoption” happened. I define an undocumented adoption in this context, also known as a nonpaternal event (NPE) or false paternity, as any event that causes the surname of record to be different than the biological surname.  The biological surname is that of the man who contributed the Y DNA.  These events, although often thought of negatively are sometimes very positive and loving – such as adoption.  Of course, some are less positive, but one can’t assume in either direction without evidence.  In my experience the most common historical reasons for a mismatch between surname and biology is that a child took his step-father’s surname or that the child was born out of wedlock and took their mother’s surname.

Reasons for a mismatch between surname and biological paternal lineage can be:

  • Adoption (contemporary or historical)
  • Sperm donor
  • Stepson taking step-father’s surname
  • Mother pregnant outside wedlock and child takes mother’s surname
  • Name change
  • Accepted multiple intimate partners (think wife-swapping or polygamy)
  • Culturally ignored multiple intimate partners (think slavery)
  • Infidelity
  • Rape

Let’s say in our example that our tester’s ancestor was born to an Estes female out of wedlock.  The illegitimate child took the mother’s Estes surname – but carries the Y chromosome of his father whose surname is not Estes. Today, several generations later, the tester carries the Estes surname handed down to him through several generations of Estes males, so his presumption, of course, is that he also carries the ancestral Estes Y DNA.  But he, ahem, doesn’t.

His test results come back and the first clue is, of course, that he doesn’t match any Estes men on his results page. He reaches out to me as the Estes project administrator, and I compare his results with Abraham to see how distant his results really are.  And the answer is….drum roll…pretty darned distant.  His results are shown in the row below green Abraham.

STR false paternity

As you can see, when compared to reconstructed Abraham, it’s quite obvious that the new Estes tester is biologically not an Estes on his Y DNA. In fact, he has a genetic distance of 7 out of 12 markers, so very clearly not a match.

How Many Mutations Is Too Many?

Family Tree DNA has set up Y DNA matching thresholds at levels that include relevant matches and exclude non-genealogically relevant matches.  For someone to be listed as your match, they need to have no more than the following total number of mutations difference from your results on any given panel.STR Match mutations

Depending on where your mutations fall, in which panels, you can have too many mutations to match at 25 markers, for example, but match at 37 or 67 because more mutations are allowed, and your mutations just happened to fall in the first panel or two.

The number of mutations allowed is the same as genetic distance.

What is Genetic Distance?

You’ll notice on the Y DNA matches page that the first column says “Genetic Distance.”

STR genetic distance

Many people mistakenly assume that this is the number of generations to a common ancestor, but that is NOT AT ALL what genetic distance means.

Genetic distance is how many mutations difference the participant (you) has with that particular match. In other words, how many mismatches in your DNA compared with that person’s DNA.  Looking at the example above, if this is your personal page, then you mismatch with Howard once, and Sam twice, etc.

Counting Genetic Distance

Genetic distance, however, can be counted in different ways, and Family Tree DNA utilizes a combination of two scientific methods to provide the most accurate results. Let’s look at an example.

In the methodology known as the Step-Wise Mutation Model, each difference is counted as 1 step, because the mutation that caused the difference happened in one mutation event.

STR genetic distance calc

So, if marker 393 has mutated from 12 to 13, the difference is 1, so there is one difference and if that is the only mutation between these two men, the total genetic distance would be 1.

However, if marker 390 mutated from 24 to 26, the difference is 2, because those mutations most likely occurred in two different steps – in other words marker 390 had a mutation two different times, perhaps once in each man’s line.  Therefore, the total genetic distance for these two men, combining both markers and with all of their other markers matching, would be 3.

Easy – right?  You know this is too easy!

Some markers don’t play nice and tend to mutate more than one step at a time, sometimes creating additional marker locations as well.  They’re kind of like a copy machine on steroids. These are known as multi-copy (or palindromic) markers and have more than one value listed for each marker.  In fact, marker 464 typically has 4 different values shown, but can have several more.

The multiple mutations shown for those types of multi-copy markers tend to occur in one step, so they are counted as one event for that marker as a whole, no matter how much math difference is found between the values. This calculation method is called the Infinite Alleles Mutation Model.

str genetic distance calc 2 v2

Because marker 464 is calculated using the infinite alleles model, even though there are two differences, the calculation only notes that there IS a difference, and counts that difference as having occurred in one step, counting only as 1 in genetic distance.

However, if one man also has one or more extra copies of the marker, shown below as 464e and 464f, that is counted as one additional genetic distance step, regardless of the number of additional copies of the marker, and regardless of the values of those copies.

STR genetic distance calc 3 v2

With markers 464e and 464f, which person 2 carries and person 1 does not, the difference is 17 and the generational difference is 1, for each marker, but since the copy event likely happened at one time, it’s considered a mutational difference or genetic distance of only 1, not 34 or 2. Therefore, in our example, the total genetic distance for these men is now 5, not 8 or 38.

In our last example, a deletion has occurred, which sometimes happens at marker location 425. When a deletion occurs, all of the DNA at that location is permanently deleted, or omitted, between father and son, and the value is 0.  Once gone, that DNA has no avenue to ever return, so forever more, the descendants of that man show a value of zero at marker 425.

STR genetic distance calc 4 v2

In this deletion example, even though the mathematical difference is 12, the event happened at once, so the genetic distance for a deletion is counted as 1. The total genetic distance for these two men now is 6.

In essence, the Total Genetic Distance is a mathematical calculation of how many times mutations happened between the lines of these two men since their common ancestor, whether that common ancestor is known or not. In fact, we use genetic distance as part of our calculations to attempt to discern when that common ancestor lived, if we don’t know who he was.

One of the reasons that mutational difference (genetic distance) is important is because the TIP calculations utilize the number of mutation events, and the estimated time between mutation events, to determine the range of dates and confidence levels for the time to the most recent common ancestor (MRCA) calculations between any two matching men.

Please note that on July 26, 2016 Family Tree DNA introduced changes in how the genetic distance is calculated for some markers to be less restrictive.  You can read about the changes here.

How Often Do Mutations Happen?

A very common question about STR mutations is “how often do mutations happen?”

A mutation can happen any time. I have seen 2 mutations between a confirmed father and son, and I have seen 8 generations elapse with no mutations.  So, in essence, mutations happen whenever they darned well feel like it.  In reality, the time between mutations varies widely, but we can calculate the average and utilize that number.

Family Tree DNA provides us with an estimation tool, called the TIP calculator. You can see the orange “TIP” icon listed with each match below.


You use the calculator to compare the results of any two men who match each other to estimate the probability of when they shared a common ancestor.

STR TIP input

The TIP calculator estimates number of generations at various confidence levels between any 2 matching men. However, please keep in mind that the TIP calculator has to use statistical averages, which is equivalent to “one size fits all.”  In truth, one size doesn’t fit anyone particularly well, and some people not at all,  but it’s the best we can do.

STR TIP output

In this case, these two men being compared are 3 mutations different at 111 markers, and they are proven genealogically to be 8.5 generations apart, counting the parent as generation 1, and counting Abraham Estes as generation 8 for one man and 9 for the other.

So, you can see, at the 50th percentile, where statistically you are as likely to be incorrect in one direction as the other, the estimate is about 4.5 generations.

The TIP calculator is sometimes very accurate, and sometimes not so much. It’s a tool, not a crystal ball.  Don’t we wish we had that crystal ball…oh yes…and a time machine too!!!

In Summary

Utilizing Y DNA to compare your family’s Y DNA to others is a wonderful genealogical tool. DNA testing is becoming an expected part of the Genealogical Proof Standard, an integral part of a “reasonably exhaustive search.”

You can prove, or disprove, your lineage. You can find your biologically accurate line.  You can combine the results of several descendants to recreate your ancestor, and then identify line marker mutations that will help other testers in the future identify their lineage.  You can test even further, if you want, and explore all of the possibilities of deep ancestry.

Furthermore, having reconstructed your ancestor, when you do finally hit that “Holy Grail” and a male who lives in the small village overseas where your ancestor originated tests his DNA – and matches your ancestral DNA values – you’ll know that the match is genuine – and you can claim them as “yours.”

Even though Y DNA testing can only be performed on males, because only males carry the Y chromosome, females can most certainly participate by recruiting appropriate males and sponsoring tests on their ancestral lines. Lack of a Y chromosome doesn’t stop anyone, just maybe slows you down for just a tad!

Have fun, enjoy, test your Y DNA lines, contact your matches and make your ancestor come alive once again through the legacy of what your ancestor left to you…their, now your, DNA.



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51 thoughts on “Concepts – Y DNA Matching and Connecting with your Paternal Ancestor

  1. This was very interesting. Maybe now I can further investigate why my brother’s YDNA seems to change to a different surname back in Ireland a couple of hundred years ago…

  2. Another great article, Roberta. I’m going to recommend this to those in my group that keep saying they don’t understand DNA–even though I”ve convinced many to do advanced testing and even SNP testing.

  3. I must thank you for this article. It is the best yet.

    I have been on a quest for the last few years to find out who my biological great grandfather is. My Dad’s father (I’m female) was born out of wedlock in a foundling home in MI. I have found his birth record. It lists father “unknown”. My great grandmother kept him and married when my grandfather was about 2. He took his stepfathers surname (Adams). This was the 1880’s. My Dad’s brother is living (94yrs) and had his YDNA67 done for me through Family Tree. Since the results “came in” I have tried to make heads or tails out of it. This article is the first that makes any sense to me and I’ve read many. Thanks you so much. Maybe now I can find a surname to go with the missing branch of my family tree.

    Sincerely, Laurel Adams in CT

  4. Excellent post! I would like to add some more impact to what you have already written because I really have personally experienced probably the most challenging aspects of all forms of genetic testing, and therefore feel qualified to comment.

    To understand the FTDNA standards of genetic distance, we must also understand the way that they count distance. Their algorithm employs the IAM (infinite allele model) towards genetic distance, which counts each mutation towards difference. I would argue that in light of more understanding that we should be employing the stepwise model, which counts each mutation as a single event despite if it is a four step jump, a two step jump, or a one step jump. Why is this important? Because if one has a null value, for example, it will not be counted as a difference of 15, but, a difference of 1 (but probably should be zero), and it will not knock valuable matches out of one’s list. The second reason why it is important is if one has a recLOH, another form of copying error. The mutational difference here could be as little as one,two, or even three,but should be treated as a single event towards genetic distance. Finally, there are the differences on the palindromics- in my experience these are one time events as well, and when analyzing extremely off modal haplotypes within a group, this buttresses the case for employing the stepwise model towards calculating genetic distance. I have personally been impacted by all of these factors, which made identification of my true paternal line a very lengthy challenge.

    Now, my paternal family (Naramore) is a GD=38@111 from the modal haplotype of DF21. I frankly do not know how we are DF21, but we carry the mutation which tells me that there is a whole lot left to learn about DF21. With that said, all Naramores worldwide share a common ancestor. I have been able to confirm this by triangulating haplotypes from two separate American Naramore lines who do not connect until back in Dartmoor, England, with a man who is from Dartmoor, England. Our genetic distance @111=16 on the far end, and 12@111 on the low end. This according to FTDNA knocks us out of relatedness, but we know better. I am a gd=3@111 with my half first cousin as well as a gd=1@25 with my own brother. We are most likely the exception rather than the rule, but indeed, the stepwise model would have cured a lot of the gd issues that we were experiencing initially.

    Thanks for the well versed “liturgy”!

  5. I learn from all of your articles but these concept papers contribute so much to help me better understand dna testing results. Thank you!

  6. Thanks so much for this article, Roberta. I had my male 1st cousin tested during the Christmas sale but have been totally unable to figure out what to do with it. His best match is G2 but I have to go back at least 10 generation to get a TIP confidence rating over 90%. Unfortunately that person did not respond to my email but I think I found him with Google. Interestingly all of my generation are about 90% Ashkenazi but this person appear to be Catholic. I do have a trace of Sephardic autosomal genes and suspect that he may be from a Converso line of the family. There were no Surname matches. In fact I haven’t found anyone else named Genis who has done any genetic testing so far. Do you have any suggestions on what I should try looking for next?

    • The entire purpose of these articles to help, so I’m glad that you’ve added the article to the project. I think I’ll do the same to my projects too. Thanks for the idea.

  7. Great article, Roberta! This is best explanation of determining GD using the infinite alleles model I have seen yet. Thank you!

    As a follow-up question on mutations in general, in your experience, are back mutations equally likely to occur as forward mutations?

  8. Well done, Roberta, even by your usual high standards. Your caveats regarding those pesky statistical limitations are especially helpful. I have spent four years and 21 DNA tests trying to identify my paternal grandfather and have been lured way off the trail several times by statistical quirks. One example: a 2nd cousin will not show as a yDNA match at FTDNA simply because he has a null at DYS393. Another: a “half-cousin plus 3rd cousin” matches me for 816 cM of aDNA, rather than the “expected” 425-525 cM, convincing me that we must be related on both sides of his family. Not. And most recently, a 3rd cousin will not match me at FTDNA, but shows three segments totaling 21 cM when I set the GEDmatch parameters to 5 cM and 500 SNPs … and two of those segments are nearly adjacent and fully “bridged” by a triangulated single segment from a know relative. So your message is spot on: while the averages are generally helpful, they can be very misleading. Thank you for all of your terrific posts.

      • And then there’s the man who drowned in a river with an average depth of 12″. For the benefit of your readers, I should probably mention one more misleading statistic. I have a 35/37 yDNA match with a man who … given our triangulated common ancestors and documentary evidence … appears to be my 3rd cousin. While 35/37 does not make a strong case for that relationship, when you look at the details you see that we are both just one-off the modal haplotype, on two different fast-mutating markers … DYS449 and CDY. It is unlikely, but perfectly plausible, that our respective lines each had a single mutation over four generations. But if I didn’t have the aDNA results and documentary evidence, I probably would have dismissed this man as a far more distant match.

  9. Hi
    I have always been puzzled on why Ftdna give us genetic distance on the “red” fast mutating data.
    I have always had more success by excluding these red ones.

    My theory is that I know my recent family ( last 200 years ) and so by excluding these red ones I might find people who will be GD closer to me.

    I wonder if it would make a major difference to your relationship data since you have a great amount of family data…

    • If I disregard all the red (fast-mutating) markers, I have four 35/35 yDNA matches, all the same surname … not mine.

  10. I communicated with some experts, and was told that my husband Bob has few clade mates. His clade likely originated about 1375BC (range 1950BC-750BC). He showed up in the Martin group. He’s U106-RS15510+.He took the L48SNP test and is negative for the only currently known subclade. We probably won’t know in our lifetimes where his group originated. We were told to ask FTDNA to take 2 vials to hold for future testing, and have sons and grandsons test later. I’ve been telling him all along that he must be “the missing link”.I’d like to know who may match him. Sincerely, Susan MacNeill

  11. Fantastic article, Roberta. It’s a very helpful primer. I’m currently working to recreate the Y-DNA markers for my 5th great-grandfather in order to hopefully learn the identity of his father and his ancestral origins. He had 7 sons who lived to adulthood, and I’ve tracked down living male descendants for each of them. To-date, descendants of 4 of the sons have tested. The results have illustrated many of the points you raise here, particularly about the random nature of marker mutations. I’m eager for the day when I hit on the Holy Grail, as you mention, and find a match overseas from the yet-unknown ancestral village.

    For your readers who may be casually waiting for matches to come along and land in their lap, I advocate a more proactive approach. If you suspect a link to a particular line, actively trace descendants and encourage them to test. The sooner you have results – regardless of whether they’re a match or not – the sooner your research can move on (hopefully closer to the answers sought).

  12. I have a real example that I’d like to run by you. In the surname project on FTDNA that I administer, there are 3 kits for people that all have the same surname, and are known to have a common ancestor according to their documented genealogies. At 37 markers, kits A and B have a genetic distance of 2, kits B and C have a genetic distance of 3, but kits A and C have a genetic distance of 5. At 37 markers, FTDNA would say A and B match, B and C match, but A and C do not. Since we are reasonably sure the documented genealogies are all correct, for purposes of the project could all three kits be grouped together, or should kit C be in a group of its own?

  13. Roberta, this is not a comment directly addressing this column, but I don’t know where else to address it. I have recently located two male kinsmen who have agreed to do Y DNA testing if I arrange for it. After the recent changes, would you please recommend a testing agency? Will I be able to transfer results to my account? Thank you in advance. Gaye Ingram

    • Y DNA testing is only available fro Family Tree DNA and no you cannot transfer to Ancestry. If you want them to go an autosomal test they can do that at ancestry and transfer those results to Family Tree DNA.

      • What I want is to be able to get results for male lineage. I apologize for being uninformed. While research is not new to me, genetic research is.

        • If you want the male Smith lineage, then you need a male Smith from that line to take the Y DNA test at Family Yree DNA. I recommend 37 markers or 67 or 111 markets. The link is on the sidebar of the blog.

  14. Mrs Roberta Estes, which are Y STR’s or Y SNP’s DNA testing were more accurate to learn more to determine the Y Chromosome Haplogroups? I think and i hope when my Y Chromosome have an extremely high degree of accuracy because i already tested my Y Chromosome both Y111 STR and the Big Y SNP’s testing and I have both Y STR’s and Y SNP’s Raw DNA Results. FTDNA Kit No: N112762.

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  17. I had my Paternal Uncle tested. Their is not one Stephens surname among his matches and only one (different surname) who has listed a Stephens as his ancestor ????????

  18. Good Article. I matched 2 men at 67 markers. One with a GD of 1 and the other with a GD of 3. They match with a GD of 2. They have the same surname. Mine is not the same as mine. Are we related?

      • Thank you for the reply.

        I should have also said that none of us match on autosomal DNA. They share a MRCA born in 1620. They are 9th cousins once removed. My haplogroup is J-Z18297. One of them is J-Z1853. The other I only know is J M267.
        My thoughts are that I am closer to the one with a GD of one than the other one and I am closer to the one with. GD of one than he is to his cousin. The one I am closest to and I share a MRCA closer to me than their MRCA. We all three share the common ancestor from born in 1620.

  19. Thank you for your reply. Is it reasonable to conclude that I am more closely related to the one at a GD of one than the one with a GD OF 3 and more closely related to the one with GD of one than they are to each other? I know that they descend from two sons of theIr MRCA and are 9th cousins once removed.

    • Dennis – In my experience, No and No. I run a small family project with nine testers, all at Y111. They all share a common ancestor born about 1765. As an example, one man, let’s call him “W” has four GD=1, two GD=2, and two GD=3 in the group. Would it be reasonable to conclude “W” is more closely related to the GD=1 folks than the GD= 2 or 3 men? Statistically you might think so but in reality the GD=1s are 3C1R, 4C, 5C, and 5C. The GD=2s are W’s own son and a 4C1R. The GD=3 are 3C and 3C1R. So at 111 markers, he appears closer to two 5th cousins than to his own son and closer to 4 & 5Cs than 3Cs.

      As an example to the second question, consider the GD=3 who is the 3C1R to “W”. He is “J.” “J” is a GD=4 to his 2C “D” while “D” is a GD=1 to “W.”

      Could someone else have a different example where your scenario totally fits? Certainly. But as Roberta points out, statistics are great but we have to be careful when looking at individuals because “mutations happen whenever they darned well feel like it.” Good luck in your quest!

      • I assume all are in the same haplogroup. It would be interesting to know what the Y DNA tip from FTDNA showed about their common ancestor.

      • Dennis – yes, all are estimated as R-M269 (no terminal SNP testing done for any of them).

        Re: TiP reports – below are the TiP number of generations to 50% and 90% (eyeballed)
        3C1R 1.8, 4.8
        4C <1, 3.0
        5C 1.8, 4.8
        5C <1, 3.0

        son 3.0, 6.5
        4C1R 3.0, 6.5

        3C 4.4, 8.5
        3C1R 4.4, 8.5

  20. Pingback: Using Spousal Surnames and DNA to Unravel Male Lines | DNAeXplained – Genetic Genealogy

  21. On a hunt for the true identity of my husband’s paternal grandfather and faced with a list of Y DNA matches, I was excited to see a genetic Distance of one by one of the names in the 25 marker column and 2 in the 37 marker column. Of course I was disappointed to learn that that doesn’t mean a close relationship. It could represent one generation but as easily eight according to your helpful article.

    Have you any recommendations, specialists, articles to read… To help us plan through the othe have you any recommendations, specialists, articles to read… to help us Identify this mysterious grandfather? Our search is complicated by the fact that this grandfather was an Ashkenazi Jew and the names of all of the “cousins” on the list of YDNA matches are ALL different!

  22. My first cousin (CC) and another person (TC) are a match at 110/111. We know who our gg gf was (R C) he knows who his gg gf was (WC). WC is likely the MRCA and is the father of our gg gf (RC). But, what is the probability the MRCA (WC) is in fact our ggg gf? To add more confusion, TC has two more closely related cousins than us. He also matches one of them at 109/111 (LC) and the other at 108/111 (G C). In fact, those two cousins (LC and GC) (are 1st cousins once removed from each other) differ at 108/111. Is the Y 111 test less reliable for 1st or 2nd cousins? I believe (TC) that tests 108/111 with GC are 3rd cousins, whereas my cousin (CC and TC are 3rd once removed). I’ve tried the TIP calculator when we know 4 generations, but it makes no sense to me as it seems to show a lower confidence level than if we know nothing and that doesn’t make any sense to me. Thank You, Steve

  23. Could you enlighten me what happens when a male ancestor does not have a male child, only a female one, and the next male child is born when this female child has children and then of course her husband’s Y-DNA is passed on to the male child and so on. How do we go about finding this male ancestor if he was an unknown entity and did not have a male child with the known female ancestor. Can you still find him through other descendants he may have? I am a female descendant of his daughter’s male child and matched to the paternal side of a father and daughter who got tested at 23andMe, where I was tested as well. To make things even more complicated, he was born out of wedlock as well but did know who his father was. His paternal surname is not the same as mine, but then I wouldn’t expect it to be. Any further light you could shed on this type of situation would be appreciated

      • The ancestor is my great-grandfather, an unknown person. He had a daughter with my great-grandmother, so his Y-DNA would not have been passed on to her. When my grandmother married, her husbands Y-DNA was passed on to my father. Would this unknown ancestor’s DNA show up in my DNA test? I had my DNA tested at 23andMe as well as at The matches in question also match me on both test sites. Can it be the unknown great-grandfather?

        Gisela Greenlee

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