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Understanding Your Y-DNA Test Results
By Jim Strachan
August 30, 2008

The author of this article, Jim Strachan, is the Group Administrator for the
"Strachan Clan" Y-DNA Project at FamilyTreeDNA.com.  


 

In the science of genealogy, Y-DNA is quickly gaining significant recognition in assisting various families to re-connect. 

The accurate spelling of surnames, and public records documenting family genealogy (for example, birth certificates and marriage licenses) are a relative modern invention typically starting in the mid- to late-1800s.  Moreover, in Scotland "irregular" or "runnaway" marriages was a practice of marriage without government license or documentation.  An irregular marriage came about in one of three ways: by mutual agreement, or by a public promise followed by consummation, or by cohabitation and repute.  These irregular marriage registers are not held centrally, and indeed the whereabouts of some is unknown. It has been suggested the rate of unrecorded irregular marriages may be as high as 30 percent. 

This lack of genealogical primary documentation is preventing most families from tracing their heritage and family lineage beyond 150 to 200 years.  To help usurp this proverbial roadblock, genealogist are finding Y-DNA testing to be of significant assistance.

 

Y-DNA testing is widely used in various surname projects, as it tests male DNA.  Obviously, only testing male DNA in a surname project makes sense, as surnames are passed through the male line.  By testing various markers ("Alleles") these projects can help identify lost family lineages. 

There are several advantages to Y-DNA testing in addition to identifying the genealogy profile of your male family line. 

  • It may provide clues of where to focus additional traditional documentary genealogical research;

  • You may be able to verify that your traditional documentary genealogical work is accurate and scientifically verified; and

  • You may be able to obtain clues as to the village of origin in Europe of immigrant ancestors.

  • You may identify cousins living in opposite ends of the ocean you did not know you had. 

My DNA Report

At this point, let's assume you've swabbed your cheek, and submitted your Y-DNA to a surname project... now what?  If you submitted your DNA through FamilyTreedDNA.com, you should be receiving a certificate with a chart that looks similar to the one below....

H
A
P
L
O
3
9
3
3
9
0
1
9
3
9
1
3
8
5
a
3
8
5
b
4
2
6
3
8
8
4
3
9
3
8
9
|
1
3
9
2
3
8
9
|
2
R1b2 13 25 14 10 11 14 12 12 12 13 13 30

Sample of a 12-Marker test
 

Haplogroup

The "HAPLO" column shows what haplogroup you belong.  A Y-DNA haplogroup is defined as all of the male descendants of the single person. Your haplogroup defines a general population, if you will.  For example, haplogroup R1b1 and its subclades are generally identified with the Picts, an iron age people who inhabited much of Scotland, and migrated 10s of thousands of years ago through Ireland and/or France.

Haplogroup R1b1 = Pict or Celt origins. 
Believed to have originated in France, then migrated to Ireland, then to Scotland.

Haplogroup I is associated with the Vikings or Norse, who invaded Britain in 900 AD. 

Haplogroup I = Norse / Viking origins.
Believed to have originated in Scotland as a result of the Norse Invasion.

Haplogroup R1a = Viking - see here
Believed to have originated in Scotland as a result of the Norse Invasion.

Haplogroup J2, is associated with the Romans, who also invaded Britain much earlier in about 90 AD. 

Further reading on Haplogroups can be found on http://en.wikipedia.org/wiki/Haplogroups

 

Alleles or Markers & Calculating Genetic Distance

You do not necessarily need to concern yourself with the genetic markers or calculate the genetic distance.  The Group Administrator for the Strachan Project does this annually, and places those with a family-match into various "family subgroups" (see Strachan Clan Project Results).  Additionally, you can log into your account at FamilyTreeDNA, and they can show you at anytime what genetic matches you have.

However, for those with inquiring minds...

The Alleles, or markers are provided to the right of your haplogroup, and are used to identify recent family lineages .  After all, not all individuals who belong to haplogroup R1b1, for example, have the same genetic markers.

The first step is to calculate the genetic difference.  This is done by simply comparing your alleles with another group members alleles, and calculating a 'genetic distance.'

  3
9
3
3
9
0
1
9
3
9
1
3
8
5
a
3
8
5
b
4
2
6
3
8
8
4
3
9
3
8
9
|
1
3
9
2
3
8
9
|
2
person1 13 23 14 10 11 14 12 12 13 13 13 29
person2 13 23 14 11 11 14 12 12 12 13 11 29
 
genetic distance 0 0 0 1 0 0 0 0 0 0 2 0

Genetic Distance Chart
Source: FamilyTreeDNA.com

From the above chart, we add the row "genetic distance" together, and in this example, the genetic distance between these two people in the table equals 3. 

The example provided here is a 12-marker test.  Unfortunately, Europe was settled by just a few homogenous peoples, and thus the DNA in Europe is less diverse then any place on the planet.  It is for this reason we require a 37-marker Y-DNA test in order to be listed in our project results.   Testing fewer than 37-markers will not yield sufficient information given the homogeneous nature of DNA in Europe.  Also, you do not need to test more than 37-markers.  From a statistical perspective, the 37-marker test is a statistically relevant sample population, and provides exactly the information we need.

FamilyTreeDNA.com

We require all participants to use the lab at familyTreeDNA.com.  They ensure blind testing, and most importantly have one of the preeminent labs in the world as it pertains to Y-DNA testing and project administration.

If you have been tested previously through a different lab, FamilyTreeDNA does offer substantial discounts to re-test with them.

 

Interpreting Genetic Distance Within Surname Projects:  37-Markers

37 Markers
  • Distance: 0 - Very Tightly Related

    37/37 Your perfect match means you share a common male ancestor with a person who shares your surname (or variant). Your relatedness is extremely close with the common ancestor predicted, 90% of the time, in 5 generations or less and over a 95% probability within 8 generations. Very few people achieve this close level of a match. All confidence levels are well within the time frame that surnames were adopted in Western Europe.

  • Distance: 1 - Tightly Related

    36/37 You share the same surname (or a variant) with another male and you mismatch by only one 'point' at only one marker--a 36/37 match. It's most likely that you matched 24/25 or 25/25 on a previous Y-DNA test and your mismatch will be found within DYS 576, 570, CDYa or CDYb. Very few people achieve this close level of a match. Your mismatch is within the range of most well established surname lineages in Western Europe.

  • Distance: 2 - Related

    35/37 You share the same surname (or a variant) with another male and you mismatch by only two 'points' --a 35/37 match. It's most likely that you matched 24/25 or 25/25 on previous Y-DNA tests and your mismatch will be found within DYS 439 or DYS 385 A, 385 B,389-1 and 389-2, from our first panel of 12 markers, or from within the second panel at DYS #'s 458, 459 a, 459b, 449, or within 464 a-d. If you matched exactly on previous tests you probably have a mismatch at DYS 576, 570, CDYa or CDYb in our newest panel of markers. Your mismatch is likely within the range of most well established surname lineages in Western Europe.

  • Distance: 3 - Related

    34/37 You share the same surname (or a variant) with another male and you mismatch by three 'points' --a 34/37 match. Because of the volatility within some of the markers this is slightly tighter then being 11/12 or 23/25 and it's most likely that you matched 24/25 or 25/25 on previous Y-DNA tests. Your mismatch will most often be found within DYS 439 or DYS 385 A, 385 B,389-1 and 389-2 from our first panel of 12 markers, or within the second panel: DYS #'s 458, 459 a, 459b, 449, or within 464 a-d. If you matched exactly on previous tests you probably have a mismatch at DYS 576, 570, CDYa or CDYb in our newest panel of markers. Your mismatch is likely within the range of most well established surname lineages in Western Europe.

  • Distance: 4 - Probably Related

    33/37 You share the same surname (or a variant) with another male and you mismatch by four 'points' --a 33/37 match. Because of the volatility within some of the markers this is about the same as being 11/12 and it's most likely that you matched 23/25 or 24/25 on previous Y-DNA tests. If you matched exactly on previous tests you probably have a mismatch at DYS 576, 570, CDYa or CDYb in our newest panel of markers. If several or many generations have passed it is likely that these two lines are related through other family members. That would require that each line had passed a mutation and one person would have experienced at least 2 mutations. The only way to confirm is to test additional family lines and find where the mutations took place. Only by testing additional family members can you find the person in between each of you...this 'in betweener' becomes essential for you to find, and without him the possibility of a match exists, but further evidence must be pursued. If you test additional individuals you will most likely find that their DNA falls in-between the persons who are 4 apart demonstrating relatedness within this family cluster or haplotype.

  • Distance: 5 - Only Possibly Related

    32/37 You share the same surname (or a variant) with another male and you mismatch by five 'points' --a 32/37 match. It is most likely that you did not 12/12 or 24/25 or 25/25 in previous Y-DNA tests. If several or many generations have passed it is possible that these two group members are related through other family members. That would require that each line had experienced separate mutations and one person would have experienced at least 2 mutations. The only way to confirm or deny is to test additional family lines and find where the mutation took place. Only by testing additional family members can you find the person in between each of you...this 'in betweener' becomes essential for you to find, and without him only the possibility of a match exists, further evidence should be pursued. If you test additional individuals you must find the person whose DNA results falls in-between the persons that are 5 apart demonstrating relatedness within this family cluster or haplotype.

  • Distance: 6 - Not Related

    31/37 is too far off to be considered related, unless you can find an “in-betweener’ as for determining ‘Only Possibly Related,’ above. It is important to determine what set of results most typifies the largest number members of the group you are 'close' to matching. You may be 31/37 with an individual, but 34/37 with the center of the group, and your potential relatedness to him is through the center of the group.

  • Distance: > 6 - Not Related

    You are not related and the odds greatly favor that you have not shared a common male ancestor with this person within thousands of years. You are probably even in different Haplogroups on the Phylogenetic tree of Homo Sapiens.

  • ** Note: When an STR marker comparison differs by more than one, the genetic distance rather than the number of mismatching markers is taken into consideration. This is because some STR markers have a low mutation rate making each step difference as meaningful as mismatches on additional markers.

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