I'm not sure how John Walden derived his stats, but they seem overly pessimistic to me. This is based on 23andMe's algorithm, which used simulated pedigrees with real genotype data. They created artificial descendancies, mating random genotypes and creating descendants according to recombination probabilities. This was done for 10 generations. Then they looked at matching segments to see if they could be traced back to the founders. Perhaps 5-10% of matches at the 7 cM failed this test, so it happens, but it's not nearly as gloomy as John Walden depicted. The 10 cM level at 23andMe would be about 0.13% and classified as a 3rd to distant cousin. What many people fail to consider is that most cousins will be on the distant end of the range, simply because you have many more of them. Ann On Sat, Jan 7, 2012 at 6:29 AM, Jim Bartlett <[email protected]>wrote: > Dear Tim, > > Thank you for outlining this process. I have very mixed emotions at this > point. The main ones are betrayed and upset. I have been pushing (as in > selling) Family Finder for the last 18 months - I make presentations at the > FHCs in DC and Baltimore at annual workshops, as well as retirement > communities and genealogy clubs in the region. I'm asked to speak, because > DNA is the most technical word I use - I proclaim that no biology is needed > to use the new DNA tools for genealogy, and I keep the presentation and > discussions at that level. I have a Masters in engineering and my wife has > a PhD in biology - but I try to keep the talks at a level everyone can > understand and use. Many have taken my advice: "every serious genealogist > should take the Family Finder DNA test." > > Many of them can barely afford this test, much less be required to fund 3, > or more, in order to use it. It now appears this test is only for a very > small group of folks who truly understand it, and it's not ready for the > vast majority of genealogists. > > We've had good success with Y-DNA surname projects: "if two men have > matching Y-DNA, they have a common ancestor; if not, they don't" - an easy > rule that we can understand. > > The rules for atDNA are like Twister, very expensive, and involve many > more steps than just comparing with matches. I'm sad that I've sent so many > unsuspecting genealogists down this path. > > If I understand correctly, the simple rule for genealogy hobbyists is: > "discard all matches below 10cM, and focus on the few remaining". Later > today I'll see what that does in my case. In my 1024 23&me matches, what > should be the equivalent (to 10cM) cutoff - in percent and/or number of > segments? > > Is ANYONE finding any new cousins with FF or 23&me? By this I mean > strangers, not the close kin you already know and/or have paid for their > tests. What percent of your hitherto unknown matches have worked out? >