This is a Message Board Post that is gatewayed to this mailing list. Author: ksaxe Surnames: McConnell Classification: queries Message Board URL: http://boards.rootsweb.com/surnames.mcconnell/2482.1.1/mb.ashx Message Board Post: The mismatches for John C. and Robert A. McConnell show an interesting pattern: Marker mutation rate Robert's value John's value 449 .00830 30 31 464c .00566 16 17 576 .01022 17 20 CDY B .03531 40 41 One interesting thing that I noticed is that all of these markers have above average mutation rates. Looking at the large number of steps between the two cousins, it seems natural that the mismatches are on fast markers. However, when I asked experts about what this means for people who don't have a paper trail and are comparing matches, they all said that the speed of the mismatched markers has almost no effect on the expected time to most recent common ancestor statistic in most cases. The exception noted was for very distantly related people whose results suggested a most recent common ancestor who lived about 2,000 years ago or more. So if you are looking at a DNA match with a person who may or may not be related, it may be interesting to look at the speeds of the mismatched markers, but you shouldn't place too much emphasis on them. Whether the mismatched markers are all fast, all slow, or a combination of fast and slow generally doesn't tell you very much about the pro! bability of sharing a recent common ancestor. There's another interesting pattern here. In every case, John has more repeats at the mismatched markers than Robert does. This could be pure coincidence. If you assume that John has a 50% chance of having the higher number of repeats at each marker, there is a 1 in 16 chance that he will have a higher repeat count for each marker. There is also a 1 in 16 chance that Robert will have a higher repeat count for each marker. So it's not all that unlikely for such a pattern to occur by chance. There are also some reasons to suspect that the pattern is not simply the result of blind chance. It turns out that Guian was an older father and may have been as old as 62 when his son Alexander, John's gg grandfather, was born, and as old as 54 when his son William, Robert's gggg grandfather, was born. Anecdotal evidence suggests that older fathers are more likely to generate mutations in their offspring. Furthermore, there is a slight bias toward mutations that add repeats. It is tempting to speculate that Guian may have generated multiple mutations in Alexander leading to much of the difference in the results for John and Robert. Of course it is also possible that some of the difference between John and Robert traces to one or more mutations generated in William by Guian. John and Robert's relative Kathy would like to find a descendant of one of Guian's other sons to test. If such a man can be found and tested, they they would be able to compare results. The results of the third man on markers 449, 464c, 576, and CDY B would be of special interest. If his results matched either John or Robert on any of these markers, the matching values would probably be the same as Guian's were on those markers. The values on all other markers for Guian probably matched those of John and Robert. Wherever two of the men matched and the third mismatched, the mismatch would probably be due to a mutation in the line of the third man. The process of comparing test results for multiple descendants of the same man to deduce his probable haplotype is called triangulation. The results of triangulation are especially interesting in a case where there have been a lot of recent mutations, but it is always helpful to know the ancestral haplotype when comparing results with men who may share the same common ancestor, or, even better, an earlier common ancestor. Comparing the haplotype to the results of the other man, or better yet, a triangulated haplotype for the most recent common ancestor of that man and some male line relatives of his, leads to a more precise estimate of their relatedness than 1 on 1 comparisons alone. If the results of such a comparison suggested that more of the mutations happened in the line of one of the men, testing of another descendant of the same son would be very interesting. In the case of John and Robert, if the two descendants of that son shared the same values at any of the 4 markers, that would suggest that their most recent common ancestor (MRCA) in the line back to Guian probably had those same values, with the mutations separating them from descendants of the other 2 sons most probably having occurred between Guian and the MRCA. Mismatches would be the result of recent mutations in one of the lines. Things get really exciting for genealogists when they are able to use these sorts of techniques to explore their connections with DNA matches that haven't been linked to them by a paper trail. Important Note: The author of this message may not be subscribed to this list. If you would like to reply to them, please click on the Message Board URL link above and respond on the board.