Interpreting Results

We all share common ancestors - the question is how recently.  Is it “recent”, since the advent of surnames, long ago or very long ago?  Here is an explanation from Terry that may help interpret your results.

  • I think in these time frames
    • Within several hundred years - a shared recent common ancestor or “RCA” 
    • Since the advent of surnames (c1100).  I call this common ancestor since the advent of surnames a “CAS”
    • In the range of 1000s of years.  This is defined by men sharing the same "Haplogroup" (which can go to 10-20,000 years ago)
    • In the range of 10s of 1000s of years.  This is shown by men who do not share a Haplogroup
  • Matches are evaluated in terms of markers which have the same result. 
    • Based on a large database, a Haplogroup assignment can be made for most results - based on an assessment of the first 12 markers. 
      • Sometimes, a SNP (pronounced "snip" test is required to identify the Haplogroup.
      • Haplogroup assignments at FTDNA are color coded
        • Green - SNP tested
        • Red - estimated by FTDNA, based on matches (or near matches) to other results which were SNP tested
        • Black - other estimates of the Haplogroup
      • For those interested in exploring this a little further, Whit Athey has developed a tool to estimate your haplogroup.  Click Here .
    • If a sufficient quantity of markers match, then we can confirm a RCA or CAS
    • Once we have at least two matches at 25 markers or more, we (World Families Network) declare a "Lineage" - which is a group of men descending from a Common Ancestor
      • As we get more results, we can often define the exact result of the Common Ancestor at every marker.  We call this the "Ancestral Haplotype"
      • As we get more results, the paper trails give us insight into when and where this Common Ancestor may have lived.
    • Within a Lineage, the non-matching markers may give us more information
      • Typically, the mismatches will be only one count - except on the markers which mutate the fastest (464 and CDY)
      • We call the mismatches "Mutations"
      • If the mutation has no match - it is simply a mutation (for now)
      • If the mutation is matched by another result, we likely have an indication of a branch recent common ancestor (BRCA) who also descends from the RCA, but lived more recently and is shared by the two men with the matching mutation
      • Statistical analysis is disappointingly vague, as the mutations are pretty random, but we can still make some useful generalities - as long as we don't try to become too precise in our interpretation.  I think of these statistical results as a "fuzzy" answer.
        • One approach to this analysis is "Time to Most Recent Common Ancestor" or tMRCA" which can be reported at the 50% probability (this can very misleading)
        • Family Tree DNA's FTDNATiP calculator makes a similar calculation and reports the probabilities for each 4 generations (which they call 100 years.  Because this approach gives a range of answers, it is a more appropriate form of answer - but is not "satisfying" in simplicity) 12 markers
  • A 12/12 match of the men of the same surname usually indicates a RCA - or possibly an earlier CAS (or both)
  • Many 12/12 matches of men with differing surnames will fall apart at 25 markers - as the 12/12 resolution isn't regularly sufficient to discern relationships across differing surnames
  • A few 12/12 matches of men of the same surname also  "fall apart" at 25 markers, but most maintain a “Match” (see the Russell example below)
  • A number of 11/12 matches and most 10/12 matches fall apart at 25 markers - indicating no RCA or CAS
  • I prefer not to have to assess relationships based on 12 marker results and won't "call" a Lineage until at least two men "match" at 25 markers

On 25 markers:

  • Matches of 23/25, 24/25 & 25/25 indicate a RCA and CAS.  In shorthand - a match of 23/25 or better is even called a "Match"
  • Matches of 22/25 or even 21/25 may indicate a CAS - but probably not a RCA.   This situation requires more markers to have clear insight
  • Matches lower than 21/25 typically indicate that there is no CAS
  • When in doubt about the interpretation at 25 markers, upgrades to 37 markers provide additional clarity

On 37 markers

  • Matches of 33/37 and better indicate a RCA and CAS.  These are the ones typically called a "Match"
  • Matches of 29/37 and higher indicate a moderate to higher probability of CAS, increasing in probability as the match gets tighter
  • Some families mutate faster than others, providing additional insight as the number of results in a Lineage increases

On matches at markers with mutations, we can begin identifying the BRCAs.  This is when yDNA testing begins to directly correlate with paper trails.

  • Matches indicating BRCA are a close match to the Ancestral Haplotype, but share a mutation that is different.

  • It is possible for more than one BRCA to show on a result (see the Barton example below)

  • It is in the context of the BRCA that a 37 marker test for someone whose paper trail already puts them in the Lineage can potentially benefit themselves and others of the Lineage, as they begin to help in defining the branch structure.


Here is a sample from the Russell family, which shows men who were 12/12 (or 10/12 and 11/12)


 Real  Example*331333434333
 a30 155689929
 p    ab   | |
 l         1 2
Russell Lineage IR1b132314111114121211131329
R-2John L Russell, b 1833R1b132314111114121211131329
R-23JD RussellR1b132314111114121211131329
R-25CE RussellR1b132314111114121211131329
R-3ES RussellR1b132315111114121211131329

  1. R-2, R-23 and R-25 are all 12/12 to each other and to the Lineage I Haplotype

  2. R-3 is 11/12 to the others and to the Lineage I Haplotype

  3. It appears that all 4 men share a RCA.

Then, all men upgrade


 Real Example*33133343433344444444444444GYY4655CC44
 a30 15568992989954778944440TAA6760YY28
 p    ab   | | ab      abcd AII        
 l         1 2              HII    ab  
 o                          4ab        
Russell Lineage IR1b1323141111141212111313291591011112615192915161717111119231715191737381212
R-2John L Russell, b 1833R1b1323141111141212111313291591011112615192915161717111119231715191737381212
R-23JD RussellR1b1323141111141212111313291591011112615192915161717111119231715181737381212
R-25CE RussellR1b1323141111141212111313291891011112416192814151718            
R-3Edward Street RussellR1b1323151111141212111313291891011112416192814151718111119231514171736371212

All men have upgraded to 25 or 37 markers:

  1. The blue group - at 25 markers

    1. Each man is 25/25 to each other and to the Lineage I Haplotype

  2. The orange group

    1. Are 11/12 to each other, and 24/25 to each other. 

    2. They share a RCA.

    3. They should be separated from the blue group and become their own Lineage II (and this was done in the project)

  3. The two groups appeared to share a RCA at 12 markers - but it wasn't true - as we see at 25 markers.

    1. The orange men were 11/12 and 12/12 to the blue Ancestral Haplotype, but are 18/25 and 19/25

    2. The orange group and the blue group do not share a RCA after all.

  4. At 37 markers

    1. R-2 is 37/37 to the Lineage I Haplotype (I have additional info not shown)

    2. R-23 is 36/37 to the Lineage I Haplotype

    3. The orange R-3 goes to 25/37 to the blue Ancestral Haplotype, further confirming their different ancestry.

  5. Conclusion: The 12 marker results were useful for the blue group separately and for the orange group separately, but when they were combined, the indication was very deceptive


Here is a sample from the Barton family - showing a number of issues, with a focus on the RCA and BRCA:


Barton No.  FTDNA 37 Marker Test
Real Example H99998828389855555434466666ACC5077DD43
a30 15568992989954778944440TAA6760YY28
p    ab   | | ab      abcd AII        
 l         1 2              HII    ab  
o                          4ab        
Barton Lineage I (Haplogroup R1b)1324141110141212121313291791011112515192915151617111119231715191735?1212
B-28Josiah m CatherineR1b1324141110141212121313291791011112515192915151617111119231715191735371212
A-38William m Seppy RussellR1b1324141110141212121313291791011112515192915151617111119231715181735371212
F-04Thomas, Worsley MesnesR1b1324141110141212121313291791011112515192915151616111119231714181835371212
X-1David, m ElizabethR1b142414111014121212131329179911112515192915151617111119231715191735361212
A-07Henry m Mary ThomasonR1b1324141110141212121313291791011112515192915151617111219231715191735361212
A-12Henry m Mary ThomasonR1b1324141110141212121313291791011112515192915151617111219231715191735361212
B-39Joseph m CatherineR1b1324141110141212121313291791011112515192915151617111119231715181736361212
B-16William, of Floyd Co VAR1b1324141110141212121313291691011112515192915151617111119231715191736361212
D-09Joseph m Reb. AndersonR1b1324141110141212121313291791011112515192915151617111119231715191735361212
B-06Thomas m AbigailR1b1324141210141212121313291791011112515192915151617111119231715191735361212
A-20Thomas m FrancisR1b1324141210141212121313291791011112515192915151617111119231715191735361212


  1. Lineage I has a Ancestral Haplotype for 36 of 37 markers identified for the RCA (with no clarity for CDYb)

  2. Some BCRA branching

    1. At CDYB, with one group having a 36 and the other 37.  By reviewing paper trails, we know these two group's RCA had to be born c1620 or earlier

    2. Four separate BRCAs shown in bright green.

    3. A possible BRCA for A-38 & F-4 is shown in orange - where the paper trail doesn't help us determine if it is - or not.

    4. One match which is clearly not a BRCA at 576, where B-39 is on the opposite CDYb branch from A-38 & F-4

  3. Mutations which are not matching, providing no insight at this time are shown in blue

  4. Observations

    1. When you have a Lineage and can define the Haplotype of the RCA, you can compare men to the RCA instead of each other

    2. All these men share the RCA born c1620 or earlier

      1. B-28 and D-90 are both 36/36 to the Ancestral Haplotype (CDYb is a question) and 36/37 to each other.  Their RCA was born c1620 or earlier

      2. At the other extreme, F-04 and A-17 are 30/37 and still share that RCA born c1620 or before

      3. B-39 & B-16 share two BRCAs and are 35/37

      4. A-17 and A-07 share one BRCA and are each on a separate one.  They are 34/37 to each other, but 35/37 and 36/37 to their CDYb BRCA

    3. Whether they are 36/37 or 30/37, these men all share a RCA born c1620 or earlier.  With only one or two results, we would draw significantly different conclusions about a 36/37 than a 30/37.  However, additional results give us a different perspective.

    4. At 12 markers, A-17 and B-06 are 10/12, and at 25 makers are 22/25.  At 37 markers. they are 34/37.