This is an aspect of Genetic Genealogy that I'm sure is well known to some researchers, but that, I'm only just starting to appreciate. I've been DNA testing for ancestry heavily for a year or two, but my prime interest has been older ancestry, admixture, and population genetics. All of my early attempts to contact matches through 23andme and GedMatch, resulted in frustrated conversations with North American testers, that had no paper trail back before their ancestors emigrated. Today, I matched on AncestryDNA with a third cousin. The DNA prediction was fourth cousin, but the relationship on paper is third cousin. This was my third match, confirmed by both shared DNA segments, and by a shared paper trail to common direct ancestors. How cool is that? Finding that yourself, and other researchers, share segments of the same DNA that appear to have been inherited through recent common descent. Finding each other through the code of Life that is in our cells, and being able to see where that DNA came from in our family trees!