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How it Works

When two or more DNA test results are compared and found to be identical (or nearly so) we conclude that the individuals from which the samples come share a common ancestor. The comparison is made based on the number of loci tested in common. (One can't compare data versus no data.)

Step-by-step:

1. Order a test from a reputable company with good after-test service and a Taylor surname project. Decide how many markers you want tested.
2. Receive the test (sample) kit in the mail. It will consist of a pair of cheek swabs, instructions, and a container to mail the samples back.
3. Swab the inside of your cheek as instructed, put the swabs in the container & mail it back to the laboratory.
4. Receive your individual results in the mail or by e-mail.
5. Compare your results with others to find matches and determine the genetic distance. Here is where the payoff comes and where a project support group can be very helpful.
6. If you find matches, focus your documentary research on identifying the most recent common male ancestor.

How much testing do I need?

DNA testing costs money; there's no denying it. And, it's a waste to spend more on it than you need to. The typical 12-marker panel (the minimum offered) costs about $150; a 37-marker panel about $350. The 12-marker panel is less than half the cost of the 37 markers.

However, more of a waste is to spend some money and not get the benefits. And, there are ways to save money and still get a good result. So, we'll make some recommendations for Taylors considering Y-DNA testing:

We'll start with these facts:

1. Taylor is a common surname and was even more common in the past  than it is presently, after immigration introduced more surnames. Name alone isn't a factor to discriminate one family line from another.
    
2. Most Taylors are of English, Scots or Irish descent & fall into the R1b haplogroup, for whom the first 12 markers tested may match many people with no common ancestry for thousands of years. {If you already know that you're not R1b, you could probably get away with the smaller test.}
    
3. More markers provide a greater base for confidence in a CMA and may allow more precise determination of the probable TMRCMA. (See Rule 2 below.)
    
4. Upgrading a Y-DNA test to additional markers is more expensive than ordering sufficient markers initially. {We do recommend upgrading, however, if you have a 12-marker test resulting in many "false positive" matches. }

Recommendations

1. We recommend an "industrial-strength"  initial Y-DNA test for Taylors, no fewer than 25 markers and 37 markers is better. A 24 of 25 (or 35 of 37) marker match is considered indicative of of a CMA where an 11 of 12 match is not.
    
2. We recommend joining a Taylor Surname Project at the testing company of your choice. This will get you a better price on the testing and may yield better after-test service, depending on the activity of the project's volunteers. For example, the current FTDNA price for a 37-marker Y-DNA test as part of the Taylor Surname  project is $259, a saving of $90 over the non-project price.
    
3. We recommend following up your test results by posting them to a free database such as www.ysearch.org &/or www.ybase.org. This will give you the ability to find matches among those tested by other companies and potentially maximizes the payoff from your investment.

Who to have do the test?

There are several companies in this field and sometimes the choices are bewildering. While we have our own preferences, we recommend that you evaluate the options and make up your own mind. Charles Kerschner's website gives a list and links under the heading "Testing Companies and Organizations"; scroll down his page to find it.

Also see a sub-page, http://www.kerchner.com/kerchdna.htm, or http://freepages.genealogy.rootsweb.com/~bonsteinandgilpin/dna/ydnaco.htm.  These pages give information to help select & contact a testing company.

We have been happy about our experience with Family Tree DNA. It has excellent technical standards, good service and a fine group of Taylor Surname Project volunteers (including me) for post-test support.

Interpreting results:

Making sense out of the report you get back from the laboratory and turning it into usable information is the most difficult, and often frustrating, part of the process. Your results mean nothing except in comparison to others. A greatly over-simplified view of interpretation is this:

• Identical results

  Establish (with sufficient STR markers) certainty of a common ancestor but do not provide a reliable timeframe for when this ancestor may have lived. Y- & mtDNA change so infrequently that the most usual case is no change for many generations.

• Minor differences

  Allow use of probabilities to estimate when this ancestor may have lived. The more differences there are, the more likely it is that more generations have passed.

• Major differences

  Establish unlikelihood of a common ancestor in the direct male or female line.

We'll continue this discussion below, after you've had a chance to get some basic concepts.

Definitions

Some terms are essential to understanding genetic genealogy:

• Genealogy = A field of study which uses documentary records and other techniques & resources to identify a person's ancestors, family relationships, and other pertinent information such as dates & places of birth, marriage and death. The field is limited by the information available to (except in rare instances) historic times.
  
• Haplotype = A specific pattern in Y-DNA or mtDNA, unique to a line of descendants. If two people share the same haplotype, they must share a common ancestor within a genealogic time frame.. Haplotypes are described in short-tandem-repeat (STR) analysis as a series of loci (place) names and their corresponding allele counts. 
   
• Haplogroup = A group of haplotypes which have some common characteristics. Two people who share the same haplogroup may not share a common ancestor within the past 20,000 years. Haplogroups are classified and named according to their (believed) origins and are most useful in genetic anthropology. The name starts with an initial letter, then alternating numbers & letters are added to identify subdivisions. 

  For example, most men with the Taylor surname (like most with European ancestry) belong to the R1b haplogroup. However, the Family Tree DNA Taylor project has identified 27 groups of matching haplotypes among their participants, plus about 80 other single haplotypes. Of those 107 separate haplotypes, about 100 are in the R1b haplogroup.

  Haplogroups, being so general, are not particularly useful in genetic genealogy. A haplogroup is too  broad a description of ancestry to be of much service.
   
• Mitochondrial DNA = the DNA contained in mitochondria within the bodies of our cells. The purpose of mitochondria is to supply energy to the cell so that it can function. DNA from  mitochondria  is abbreviated "mtDNA".
   
• Y-chromosome = one of the two kinds of sex-determining chromosomes. Men have one X- & one Y-chromosome. Women have two X-chromosomes. DNA from the Y chromosome is abbreviated "Y-DNA".
   
• Autosomal DNA = the DNA of a non-sex chromosome (neither X- nor Y-). Autosomal DNA determines much of what we're about, hair & eye color for example.  It is inherited from both mothers and fathers in ways which are not completely understood, though seeming to average -- for groups -- about half from each parent .
   
• STR (short tandem repeats) is the typical analysis method for Y-DNA. It identifies loci (places or addresses) on the Y-chromosome and counts the number of repeated patterns at each locus. Here is an example of a STR result with 30 tested loci:

  Locus	Y393	Y390	Y19	Y391	Y385 a	Y385 b	Y426	Y388	Y439	Y389 |1	Y458	Y389 |2	Y458	Y459 a	Y459 b
  Alleles	13	24	14	10	11	14	12	12	11	13	13	29	16	9	9
  Locus	Y455	Y454	Y447	Y437	Y448	Y449	Y464 a	Y464 b	Y464 c	Y464 d	Y460	AN01T AP4	Y464g ||a	Y464g ||b	Y456
  Alleles	9	11	11	25	19	29	16	9	9	11	11	25	15	19	16

  Red font indicates "faster-mutating" (e.g., 1/250 generations) loci. Differences in alleles may be less significant than "slower-mutating" (e.g., 1/400 generations) loci.
   
• SNP (single nucleotide polymerase) identifies specific mutations of the DNA. It is the typical analysis method for definitive identification of haplogroups, for deep ancestry studies and for mtDNA. For example, those in the R1 haplogroup share the M343 mutation; the R1b group share the P25 mutation; the R1b1b group share the P297 mutation. (Mutations are named by the code for the research group discovering them and the order in which they're discovered.)
   
• Marker has either of two meanings:
  1. In STR testing, it refers to a place (locus) on the Y-chromosome, such as "Y385a" in the table above.
  2. In SNP testing, it refers to a specific mutation, such as "P297", which marks off one haplogroup from another.
   
• Alleles (or allele value) = the count of the number of of short tandem repetitions at a specific locus (marker).
   
• Surname Project = A Y-DNA study of a particular surname. In many cultures, a family name passes from father to son which correlates with Y-DNA inheritance. Though there are exceptions, this facilitates use of Y-DNA to identify paternal lines. Joining a project provides benefits such as discounted testing and post-test support in interpreting results.
   
• Direct Descendancy = An unbroken line of descendancy through either a paternal or maternal line:
  • Father to son to son's son to son's son's son, etc., OR
  • Mother to daughter to daughter's daughter, etc.
  There may be no intervening children of the opposite gender or the direct descendancy line is broken and the Y-DNA or mtDNA will not be inherited.
   
• Match = the degree to which DNA results are similar, often expressed as a ratio of markers (loci) in agreement as the numerator, and total markers tested in common as the denominator, e.g., 12/12, 24/25, 35/37.
   
• Genetic Distance = A measure of the difference between two haplotypes.
  • Simplified method: Differences in allele counts are added across all loci tested in common.
    • If there is a difference in allele counts of 1 in one locus, genetic distance is 1. An allele difference of one each in two loci or 2 in one locus gives a genetic distance of 2.
    • Differences are absolute; a minus on one does not cancel a plus on anther.
    • The simplified method is the one commonly meant in genetic genealogy.
  • The true scientific method is more precise & useful for inter-species comparison (e.g., humans vs. chimpanzees), but it is more complex mathematically :
    • D =−log(In) ,
    • where In = (Σ Pix•Piy)÷[(ΣPix²)·( ΣPiy²)]½.
    • Pix is the proportion of allele i in population X, Piy is the proportion of allele i in population Y.
     
• Common Male Ancestor = the ancestor established by Y-DNA to be shared by the individuals who have been tested. It is abbreviated "CMA". "MRCMA" refers to the most recent CMA, reasoning that if one ancestor is shared previous ancestors will also be shared. "TMRCMA" refers to the time  (in generations) back to the most recent common male ancestor.
  
• Confidence level = the confidence, expressed as a percentage, one may have in a statistical estimate. For example, a 90% confidence level means that one can be 90% certain a statement is true but there is a 10% chance the statement is false.
   
• Non-paternal event = any event which results in a child bearing the surname of someone other than his or her biological father. Non-paternal events may include adoptions & name changes.