Right now, there are three types of DNA tests used for genealogical purposes: yDNA, mtDNA and atDNA ......yDNA.........atDNA........mtDNA .....Father's..................Mother's .......Line.....................Line .........\***********************/.....Generation 12 ..........\*********************/......Generation 11 ...........\*******************/.......Generation 10 ............\*****************/........Generation 9 .............\***************/.........Generation 8 ..............\*************/..........Generation 7 ...............\***********/...........Generation 6 ................\*********/............Generation 5 .................\*******/.............Generation 4 ..................\*****/..............Generation 3 ...................\***/...............Generation 2 ....................\*/................Generation 1 .....................|.................Generation 0 ....................YOU \ = Father's Father's yDNA back to Adam---Men only / = Mother's Mother's mtDNA back to Eve---Men & Women * = atDNA inherited from all of your ancestors---Any Gender . = disregard only used as place holder yDNA is passed from a father to all of his sons, almost unchanged, indefinitely. This test proves a paternal / surname line. mtDNA is passed from a mother to all of her children, sons and daughters. It dead-ends in the sons, and is passed on by the daughters to all their children. This test is useful in proving the origins of the maternal line, but is probably the least useful to genealogists atDNA populates the 22 non-gender chromosomes, and is randomly inherited from all of your ancestors. In each generation, the parents pass approximately half of their atDNA to each child. When testing atDNA, the assumptions is that if you match another individual in the atDNA database with an atDNA segment over a certain length in size, that you both inherited that atDNA from a common ancestor. These matches are more difficult to prove and require a VERY mature pedigree to identify common ancestors. There are several companies that do this testing. For genealogical purposes, I recommend only Family Tree DNA of Houston, Texas. There are other companies that offer similar tests at less cost, but this is definitely a case of you get what you pay for. FTDNA originated genetic testing for genealogical purposes. The company was founded about 1998, and currently has the largest database of completed tests. They have all different kinds of certifications, and maintain the highest scientific standards. If you go to FTDNA's website, www.familytreedna.com, you will be able to find out if your surname of interest already has a project. It is better for you to be tested within a project, the cost of testing is slightly less, if done through a surname project, than if you just sign up on your own. In addition, many of the project managers provide analysis, assistance and support for the project members. This is what I do, but I know there are others project managers who have a different attitude to their projects, so I cannot guarantee you will get this help with every project. We are all volunteers, and receive no compensation of any kind from FTDNA. How deep your pockets are and how much you want to learn about your biological ancestors determines which and how many tests you take or purchase for your relatives. My recommendation is the men be yDNA tested for 67 markers. This test provides sufficient genetic information to prove or disprove family matches, which is the point of being tested. There are tests with less markers, but the results are inconclusive as a result of insufficient genetic information. If you have willing male relatives, I consider this to be the basic genetic genealogy test. The mtDNA test will tell you the biological history of your maternal ancestors. If your maternal line comes from a rare mt haplogroup [see wikipedia for definitions] it can be extremely interesting. If the haplogroup is really common, it is Ho Hum. It happens that my mt haplogroup is extremely rare. Only about 4% of the population of Western Europe has this haplogroup, and it appears nowhere else in the world, haplogroup V. atDNA testing is the upper division course in genetic genealogy. There are technical as well as human factors that make these matches VERY difficult to prove. When notified of a match and you write to people to figure out your common ancestor, many people do not respond, or they are adopted and have no idea who their ancestors are, or they only know who their posh ancestors are and have no information on the everyday folks, or they expect you to research their ancestors for them, a non-starter. BUT, having said all of that, IF, you can confirm a match, it can be REALLY exciting. It can also solidify conventionally researched pedigrees that do not have as much solid evidence as you would like to have. With two years of atDNA results and over 1,000 matches, I have only confirmed three matches and identify the common ancestor. I want to also mention genetic testing for health reasons, but will put that in another message. Marleen Van Horne