A significant question has been raised that may be puzzling others as well. >I am having trouble understanding matching on 12 markers and matching on >surname, but not related. I realize that current generations should >be the same, >but does the results rule out being distantly related? The answer is a bit complicated, so bear with me as I try to explain this. First let's look at the first 12 markers for these three kits (29401, 29557, 33183). These are marker values that are for the most part very common across many surnames. A recent study of DNA values indicates the percentage of people who also have that value. I've made a chart below to show these figures. 1 - 13 - 80% 2 - 24 - 41% 3 - 14 - 69% 4 - 11 - 51% 5 - 11 - 61% 6 - 14 - 56% 7 - 12 - 60% 8 - 12 - 71% 9 - 12 - 50% 10 - 13 - 60% 11 - 13 - 56% 12 - 29 - 48% The significant thing here is that in each case, the value is the one MOST often found for that marker. Doing a search on Y-Search for these markers, I found well over 300 different surnames that share these same 12 markers. Clearly all of these folks are not related. But what about all of those who share the same surname and these markers? Having the same surname certainly gives more weight to a possible genealogical match, but it does not guarantee it. Family Tree DNA calculates that two participants who share the same surname and the same 12 markers have a 33.57% chance of sharing a common ancestor within the last 100 years. The percentages rise the farther back you go: 200 years - 55.88% 300 years - 70.69% 400 years - 80.53% 500 years - 87.07% 600 years - 91.41% Now let's look at the known ancestors for these three participants. In each case the earliest known ancestor was living in the mid-1700's, less than 300 years ago; so the likelihood of a common ancestor one generation back based just on these 12 markers would be less than 70%. But when we look at their 13-25 markers there are too many mismatches. Are these three participants related? More than likely they are, but probably dating back to at least the 1400's or earlier. My uneducated guess would be that their common ancestor might date back to a time before surnames were commonly taken. However, it is possible that certain markers have mutated over the generations, and that these three participants must go much much farther back to find common ancestors. That is why I recommend the 25 marker test. It does two things. For those who share all 25 markers (or in some cases 24/25 or even 23/25) it gives them a more accurate timeline for when that common ancestor might have lived. For example, there is a 94.15% probability that two Bowles participants who match 25/25 share a common ancestors in the last 300 years. The reverse is also true. Someone might match on the first 12 markers, but have many mismatches on the markers from 13-25. This is a clear indication that one of two things are true: either there have been several mutations in the markers (possible, but not probable) or the likelihood of a common ancestor is much further back in time than originally thought with the 12 marker match. Another factor to take into consideration is location. If two Bowles participants match on say 23/25 and both have known ancestors who lived in Maryland for example, then the likelihood of a common ancestor tends to increase. DNA is not the ultimate answer to our search for ancestors. It is a tool that will tell us the likelihood (or unlikelihood) of an ancestor. We still have to do the research to support our conclusions. I'll use my own Bowles ancestor as an example. For years it had been believed that my John Bowles who was in Barren County KY in the early 1800's was somehow related to Elijah Bowles who was also there. Try as we might, however, we could not find any document that would prove this relationship. Then descendents from both John and Elijah Bowles did the DNA test, and we learned that the likelihood of a close match between John and Elijah was almost nil. Their numbers just don't match at all. Am I disappointed? Well, yes at first I was; but now I know that there is no longer any point in searching for that elusive document that connects them, and I can get about the business of looking for a match somewhere else. I hope this has not been too long-winded or boring. It is a difficult concept to explain. If you have other questions, please ask. Charlie Hartley Bowles DNA Project Administrator [mailto:hartley@iglou.com] Website: [http://freepages.genealogy.rootsweb.com/~gensoup/bowlesdna.html]