<Mooreedith@aol.com> wrote: > I have noticed that several 'surnames' I am researching have > programs to test willing participants for their DNA. > > These programs are directed to 'male' participants only. > > I would like to hear some educated input into why are the males only > being tested? > > Is there some scientific reasoning for this? There are two ways to track DNA on the market. One uses the Y chromosome, which only males have (being XY, females are XX). All this will tell you is whether someone on your direct male line (father's father's father's etc) shares a common ancestor with you, but this is why people feel it's so useful in studying surname distribution. The other was is the direct opposite. It looks at mitochondrial DNA, which is inherited as part of the egg cytoplasm and not the chromosomes. It therefore gives you the direct female (mother's mother's mother's, etc). As it's independant of the chromosomes, everyone has it and thus both sexes can be tested. > Also - can someone explain where they get the DNA to check against? > I'm picturing they have dug up someone's remains that they compare > with. Nope. Apart from a few famous cases such as the Romanovs, it's usually just modern DNA they look at. Think about the problems we all have just finding the correct grave stone, consider the fact that there's unlikely to be very much left to get DNA from, and then how do you you know whose tooth you've dug up? There would be contamination from just about everything. Reliable, intact DNA would be very hard to find. This is one of the reasons that there is so much debate about the use of such methods. For a start, they only give info on one of two lines, nothing about all the other ancestral lines. Then they only show a relationship, they don't show who the relative was. X and Y might find that they have a y chromosome match with Z, but they'll never know whether that common ancestor was 100 years ago, 600 years ago, or a local milkman ;) . In some cases it can be useful - I've already mentioned the Romanovs, when there were enough well-documented relatives around that the DNA of the bones could be shown to be related to descendants of Queen Victoria, but even then the determining factor was that the only missing family group from her line missing in that geographical area was the dead Czar and his wife and children. I believe that it's also been used to check the claim that an American historical figure was the father of children born to a slave (I don't remember the names involved), but again the circumstantial evidence that he owned the ancestral slave and was known to be in the same area at the same time as conception had to take place was also necessary. Otherwise it would have just shown that he and the modern descendants of that slave shared a common ancestor, nothing more. It won't help you find your ancestors. It may help you confirm two of your many ancestral lines, but it won't tell you who they were or how they fit together. It's just another tool, and one that's open to misuse. I've already seen people saying that they've been told that because they have a DNA match to someone else who's alive, that proves they descend from a given line. Not true. It proves they share an ancestor with that person - whether or not it relates to the ancestors the second person says it does depends how good his normal genealogical research was. Lesley Robertson Lesley Robertson <l.a.robertson@tnw.tudelft.nl>