This doesn't mean the company is lying when it says there's a 99.9 percent chance I'm related to those Genetic Cousins, although it may be using a broader definition of "related" than its many prospective customers might assume. With each generation, the number of ancestors a person has increases by a factor of 2 to the power of the generation. Go back five generations, adding each generation together, and you've already got 62 direct ancestors--not counting siblings, cousins, aunts or uncles. At Family Tree DNA, the best-case scenario gives you a 50 percent chance that you and your Genetic Cousins share a common ancestor within seven generations--a pool of 254 relatives--and a 90 percent chance you share a relative in 23 generations, or 16,777,214 ancestors. That is to say, if you gathered enough people to populate the state of Florida today, then added about 778,000 more, you'd likely (but not surely) find a distant relative in common with your Genetic Cousin. "If you just took any two random people and looked at their DNA," says University of London geneticist David Goldstein, "you would find some part of their genomes that was derived from a common ancestor fairly recently." And by "fairly recently," he's talking less than 23 generations back. "The question is, Does it actually say much about the similarity of people if they share DNA 15 to 20 thousand years old? No, it absolutely, emphatically doesn't."