I just re-read this article from last year. Have you seen it? https://nyti.ms/2CaZMkv
Most White Americans' DNA Can Be Identified Through Genealogy Databases
The team found that a DNA sample from an American of Northern European heritage could be tracked successfully to a third-cousin distance of its owner in 60 percent of cases. A comparable analysis on the MyHeritage site had similar results.The analysis focused on Americans of North European background because 75 percent of the users on GEDmatch and other genealogy sites belong to that demographic. To identify an individual of any ancestral background, all that is needed is a database containing two percent of the target population, according to Dr. Erlich.
-- By Heather Murphy, New York Times, published Oct. 11, 2018.