The following is an email reply of mine to a fellow researcher. I base it on the charts I found on Familytree.com about DNA and from information I received from talking directly to a DNA testing lab person in Ardmore, OK. If my premise is wrong, I'd like to know where. The lab person basically said all that can be proven is probability. And the Familytree.com charts say the best that can be done if a 50-50 change of relationship with 5 generations. Relationship can be shown with 100 percent certainty only within 30 generations or so. Also it is my premise that all Guthrie's are related back to the Guthrie's of Forfar, Scotland prior to about 1200 AD. If one of you has done or knows of a tested Guthrie that is not related to other known Scotland Guthrie's I would like to talk to that person. I think a few of these are going to show up...through unknown adoptions and illegitimate births. I exclude Guthrie's whose ancestor's were former slaves. I do know of some Black Guthrie's whose ancestor's took the Guthrie name when they were freed. ------------------ HHH, I'm looking at a markers chart as I write this. According to this chart from the Family Tree website if two individuals are tested using 37 markers all that the test would show is that there was a 50% possibility of a match within 5 generations...and there is at the same time a 50% possibility the relationship is more than 5 generations. So the actual relationship match could be anywhere from 5 generations to 35 generations. It looks like a 90 % chance between 5 and 20 generations. The laws of probability go something like this. If 100 people are tested and all of them show a 50 % chance of being related with the 5 generations then any two of these have a 50% chance of being related within the 5 generations. It won't make any difference how many Guthrie's are tested, the fact being that YOUR test will only show a 50 % chance of being related with the 5 generations. 50-50 I can do that good with a coin. Now if it is possible to combine this 37 marker test with the female DNA test so as to exclude some families it might be possible to actually prove ancestry. But you would have to be very lucky to find two female descendants (descended through female line only) that fit a pattern that fit your particular situation. Or going from the other way around. DNA tests can show that sample DNA does within acceptable probability indeed belong to a certain person. But it's still a probability not a certainty. DNA tests can prove within acceptable probability that a man is a father to a certain person. Courts will not accept DNA results that show a man to be a grandfather to a certain person and even with 37 markers matching the probability that two people are related is only 50 % if the relationship is 5 generations ago. Bottom line. It won't work as you wish. But I would still appreciate it if you would send me information on those proposed French, Irish and German origins for the name Guthrie. And please ask those folk that were interested in a DNA test to contact me. Larry lguthrie@brightok.net Larry Guthrie lguthrie@brightok.net