Hi Jim, thanks for bringing up the topic of DNA testing.I'm going to go into it in a little more detail, hoping that at least a few people beyond the two of us might eventually be interested.The point I want to make is that the type of test you suggest should be the SECOND choice, not the first, for someone newly getting into DNA testing.
What you describe is a new type of testing [autosomal SNP testing] that wasn't even commercially available until about 2 years ago.Now autosomal testing is available from FTDNA in their 'Family Finder' test, and from 23andMe in their 'Relative Finder' test.This type of test (for both males and females)can connect you with males and females from any branch of your family tree.This is in contrast to traditional Y-chromosome (STR) testing, which only matches male testees to people in the all-male patrilineal line, the line which typically has the same surname as the testee.Autosomal SNP testing is, as you point out, a very exciting development.I will talk more about the advantages in a followup post.
But an important difference to keep in mind is that traditional Y-chromosome DNA testing WILL match you to almostEVERY male who descends from your all-male patrilineal line IF they take the same test.In contrast, autosomal testing misses more relatives than it matches (importantly, it actually excludes showing matches between males who are distant relatives in the same patrilineal line).
It is well known (and stated in both companies' FAQs; see FTDNA's Family Finder FAQ #28), that if you have a proven (on paper) relationship to a specific relative who is more distant than 4th or 5th cousin, autosomal testing PROBABLY CANNOT confirm the known relationship between you and that specific distant relative.So Jim's comment that "If any man or woman who descends from one of the above persons took the Family Finder DNA test, you would probably match with me" is overly optimistic.I do not want the readers to get the wrong impression about this.In contrast, (to use Jim's example) any male Frith who (like me) descends in an all-male line from Nathaniel Frith of northern Virginia, USAin the mid-1600s, and takes a 67-marker Y-chromosome DNA test, WILL match not just me but also both of the other ~7th cousins from the same line who have already tested.With Y-chromosome testing, any Frith will likely show a reasonably close match to EVERY other Frith from the same line, even if the ancestor in common lived up to a thousand years ago --EVEN before surnames were established. (There are some caveats, but this is basically true and well-accepted.)Autosomal DNA testing has its own benefits, but this is NOT one of them.
Examples from the UK: Any patrilineal descendant of Joseph Frith born circa 1695 in Farnsfield, Nottinghamshire (great-great-grandfather of William Powell Frith), including those surnamed Alford, should match fairly closely with any other descendant.And all of these should match any Yorkshire Frith who is related but who can't show a connection on paper.I hope some day to match a descendant of Hezekiah Frith, privateer of Bermuda, with a Frith who can trace his family back to somewhere in England in the same era.I would love to be able to show a Frith of London or Kent that his line appears to have originated with the Friths of Sheffield, or of Orkney, etc.
(Females should not feel excluded from Y-chromosome DNA testing, if they have a brother, father, grandfather, uncle, or cousin available to test.It does take a bit more effort for females to find a male willing to test, but it can be well worth the effort, as demonstrated by the two females who have recently sponsored a male's test in the Frith DNA Project.Similarly, males are not limited to testing their own surname, if they can find a cousin in their wife's, mother's or grandmother's line who is willing to take a test.)
Traditional Y-chromosome DNA testing through FTDNA has a further advantage: FTDNA encourages 'Surname Projects' to be run by knowledgeable volunteer administrators, for all people with the same surname (including variants). The project administrators help people understand their test results, and how those results fit in with current knowledge of the often very sketchy family trees.Based on the test results, in some cases the administrator can offer advice for further tests or genealogical research.I have set up a DNA project for the Frith surname and several variants, with different types of information available at each of the following sites: