List members: A number of individuals researching family names have set up DNA studies for the purposes of determining or separating various branches of that name, identifying discrete locales in time where the name has been found utilizing documented genealogies, ruling out possible genealogies, and determining if name changes have occurred, i.e., Cook v. Koch.  As noted by Oxford Ancestors, the Y-chromosome  is passed down from father to son for generation after generation with little or no change. However, thousands of years of evolution have created millions of different Y-chromosomes each with their own unique genetic fingerprint. The Y-chromosome test reports this fingerprint which can then be directly compared to others as an aid to genealogical research both now and in the future. As seen from the links I have included below, Y chromosome testing requires a swab from the inside of the cheek of the male Cook be sent to the lab.  The lab will then prepare a printout showing the different loci (places) on the chromosome and  the alleles (scores) for the tested locus.  For those who descend from a female Cook line, mtDNA testing can be performed, though with fewer results.  Men and women inherit the mtDNA from their mother.  Men do not pass this to their children.  It is only passed through the female line.  The better procedure, I should think, would be to find a male Cook relative for the testing.  I would suggest that Cooks participate in such a study.  There are primarily three groups who perform such testing.  The favorite of myself and some others is Family Tree DNA.  They have been most approachable and reasonable in responding to extremely naive questions.  They seem a bit slow in keeping to the time limits they've established in the testing, but quickly respond when queried.  They could use much more information at the site as to what the results mean, along the lines of GeneTree, below.  However, they test more loci than other labs (12).  Cost is $219.00.  Further, three Cooks (including myself) have already participated at Family Tree DNA.  Oxford Ancestors does not, to my knowledge, offer a storage and comparison service for any future Cook who submits their sample.  Additionally, they are in the UK. Gene Tree has more information at their web site w/ a calculator which purportedly helps determine your haplotype.  However, it is my understanding that they do not test 12 loci, as I indicated.  There are a number of comprehensive Cook sites already up.  Participants could send their results to one of those sites for a separate page or release the information to a study coordinator.  I would volunteer to put a page up if it was of assistance.  I've included below copy and paste links to various web sites, including other family names which have performed such a study. Glen Cook General Information: GENUKI: DNA & the Family Historian: http://www.genuki.org.uk/big/genetics.html Testing Labs: http://www.familytreedna.com/ http://www.oxfordancestors.com/ http://www.genetree.com/ Name studies: http://www.mumma.org/DNA.htm http://www.duerinck.com/results.html http://homepages.rootsweb.com/~tstiddem/Pages/results.html http://www.paulcuni.com/family/dna/dnaf.htm