"Keach One" has chosen 37 Markers. What does this mean? How many Markers should you test for ? This information is from item #17 of "Frequently asked questions" 17. How far back can you determine a genetic link? All genetic tests from Family Tree DNA will provide you a probability that you and another person, who have an exact match, will have your Most Recent Common Ancestor (MRCA) within a range of time backwards. Our 12 marker test gives you the following range: 7 generations (50%) likelihood & 29 generations (95%) likelihood. Using our 25 marker test the 50% likelihood drops to 3 generations and the 95% to 13 generations. The 37-marker test tightens further to 2 generations (50%) and the 95% to 7 generations. --------------------------------------------------------------- http://www.ftdna.com/faq.html