Hello Rex (and group), Some of what has been stated by other people is wrong. Somebody wrote that the odds of having the same DNA as a cousin is slim, since the DNA gets mixed and divided every generation. That is true if we are talking about any cousin, but it is not true if we are talking about male cousins linked by a surname (I'm sure there are many on this list). Assuming no infidelity, two male CHASEs who are descendents of William will have the same Y chromosome. The chromosomes from each parent are put together and jumbled when eggs and sperm are made, this does not happen to the Y chromosome, which means that every man has "exactly" the same Y chromosome as his father, his father's father and so on. So if the Y chromosome never changes then you would think that every man in the world would have the same one, since we are all related if you go back far enough. Actually, the Y chromosome does change a tiny bit because of random mutations. So if the Y chromosome changes enough, but not too much, then you should be able to correlate surnames with Y chromosome DNA. The problem is that we (scientists) do not know how much it changes. Currently, the same group that showed that a man in Cheddar, England is a descendent of a 10000 year old mummy found there, is also checking to see if Thomas Jefferson fathered any children through one of his slaves. Keith's point about infidelity is important. Infidelity is the nightmare of most genealogists. That is assuming that you are interested in exactly who your ancestors were. We all enjoy (are addicted too) genealogy for a number of reasons (investigating, learning about personal histories and interesting characters, etc.), but one thing I hope we have in common is to find out as much truth as we can. Eventually DNA will allow us to find the mistakes and infidelities in our genealogies. Personally, I love to find tidbits of scandal in my family, it makes the investigating that much more interesting.