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 individual. The DNA signatures of individual participants can be compared to establish the likelihood of common ancestry, but 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.

1. yDNA Surname Studies.  These exploit the characteristic of both y-chromosomes and surnames to only descend by the male line.  yDNA tests can be undertaken for three reasons:
   (a) focussed testing, generally by two participants, to support or refute some specific hypothesised genealogical relationship - effectively a paternity test that is not legally binding;
   (b) blind testing, to seek and investigate genetic relationships ("matches") when compared with other participants in a data base, typically sharing a common surname, for example to explore branches of a surname, break a genealogical "brick wall", or find previously unknown cousins; or
   (c) deep ancestry studies, i.e. to explore ethnicity issues going back several millennia.
   However yDNA tests have three important limitations:
   - females can only participate through a male relative;
   - surnames only go back a millennium, at most; and
   - not all descents though the male line have inherited the surname.
2. Mitochondrial (mT) DNA tests.  These only follow the female 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 test hypothesised relationships, male and female, up to 4th or 5th cousins. 
4. X DNA tests are similar to aT tests.

• enable direct comparison with other participants using similar surnames to establish genetic relationships;
• help conventional genealogical research that has met a “brick wall”;
• ascertain the probability of two or more participants being genealogically related;
• identify branches within a Clan;
• explore, develop and promulgate new ideas.

1. To facilitate and co-ordinate STR and SNP yDNA tests, of all men bearing the surname Irwin or variant spellings thereof (including Arvin, Ervin, Erwin, Irvin, Irvine, Irving and Urwin), and of other men sharing similar DNA signatures. 
2. To assess the results of these tests in the context of the traditional division of the surname into Bonshaw, Drum and Orkney branches, and the many other branches that have been identified since the project was founded, and refine the limits of these branches.  
3. To combine these DNA test results with available genealogical data, particularly to combine the Border Irwin DNA sub-groups now being identified by the L555 haplotree with the pedigrees of members of these sub-groups.
4. To cooperate with the Irvine Clan Autosomal DNA Project to develop the potential of  Family Finder tests involving the name Irwin or its variant spellings.
5. To promote, co-ordinate and publish analysis and discussion of the results, primarily through the Study’s website, but also through other media such as the Clan Irwin Association's quarterly journal, the Holly Leaf Chronicle.
6. To enable contribution to the wider research, development and understanding of genetic genealogy.