Background and Goals


Many genealogists find DNA tests useful.  The test itself is simply a saliva sample obtained by scraping the inside of the cheek.  The privacy of each tester is protected by analyses being limited to “ancestral markers” rather than to the full personal DNA “fingerprint” or "signature".  Testers’ names are not disclosed without their consent, and their e-mail addresses are not released to non-testers.  See also Privacy Statement.  If as a prospective or existing member of our Study you have concerns about privacy/confidentiality issues please e-mail the Study Administrator.

The interpretation of DNA test results depends on the transmission of DNA remaining unchanged from generation to generation, apart from small and occasional changes (“mutations”) in one or more of the “markers” that make up the genetic elements of the DNA profile or signature of each tester. The DNA signatures of individual testers can be compared to establish the likelihood of common ancestry, although DNA test results are never 100% conclusive.  Confidence in the interpretation of test results increases as more individuals participate and as the testing and analysis techniques continue to improve.

Four types of DNA test are popular with genealogists:

      However Y-DNA tests have three important limitations:

- females cannot take a Y-DNA test, though they are very welcome to participate through a related male tester;

          - Y-DNA tests can show a change of surname in the ancestral male line,  sometimes unsuspected; and 

          - the association of Y-DNA data with surnames only goes back a millennium, at most.

2.  Mitochondrial (mT) DNA tests.  These only follow the female ancestral line, and are usually undertaken to support or refute some hypothesised relationship, or for deep ancestry studies.

3.  Autosomal (aT) DNA studies such as FTDNA’s “Family Finder” test.  These are used to "find cousins", male and female, and test hypothesised relationships, up to 4th or 5th cousins. 

4.  X DNA tests are similar to aT tests.

The primary focus of this Study addresses application 1(b) above (see also Ordering Additional Tests).  In other words, the Study is not concerned with relationships through female lines identified by mitochondrial or autosomal tests, or with Deep ancestry studies of ethnicity isssues. However individual testers may of course pursue such studies privately, and the Irvine Clan Autosomal DNA Project has been established to develop the potential of Family Finder tests (see  A summary of these findings relevant to members of this Study is now included in this Study's main results table.

The relationship of conventional genealogy with genetic genealogy (the use of autosomal, mitochondrial and yDNA tests for genealogical purposes) is often confused.

Surname Studies research genealogical relationships within a specific surname.  Such studies will typically use both traditional genealogy and Y-DNA test results.  For rare surnames the objective is to collect all the records relating to members or the surname and trace their ancestries.  For more common surnames, such as Irwin, this goal is impractical, but even without such diligence there is much to learn from studying a particular surname and its various branches.  See for example the book The Irwin Surname (see Further Reading).  

Since 2000 many Scottish Clans have launched surname DNA projects and associated websites. Such projects offer opportunities to:

Turning to the Clan Irwin itself, the genealogical context of this surname Study is discussed at GENEALOGICAL BACKGROUND and in the book The Irwin Surname: its Origins, Diaspora and Early Branches, details of which may be found at FURTHER READING.

Today over 100,000 adult males use the surname Irwin (or one of several spelling variants) throughout the British Isles, in Australasia, and, predominantly, in North America.  While many such individuals possess lengthy genealogical pedigrees, very few of these pedigrees have reliably connected the diaspora of the surname. On the other hand some 90% of the testers in this DNA Study have been able to connect their paternal pedigree with a branch of the surname identifiable by its geographic origins. 


 Goals of the Clan Irwin Surname DNA Study 


This website does not attempt to describe in detail the underlying principles and terminology of DNA tests for genealogists.  For further guidance the following websites all give good background:                                                                                                                                        

FTDNA support a web-based seminar program at:

For a good bit of up-to-date, background reading on the application of genetic genealogy to surnames see:

For those interested in deep ancestry there is a good review at

For an excellent introduction to Next Generation Sequence testing, including BigY, see

See also Further Reading and Supplementary Papers 9 - Lecture Slides