Just a note that, as Lynda indicated, it is autosomal DNA that stops appearing as a potential connection after eight relationships degrees: 6g-grandparents or 3rd cousins (each represents a distance of eight birth events to you). What is called uniparental DNA--mitochondrial DNA for your maternal line and the Y-chromosome for your paternal line--don't get shuffled and recombined with each child, so those types of tests can have validity as evidence going back many more generations than can autosomal DNA.
It's also worth reinforcing that WikiTree does no DNA matching of any kind; it can't see any DNA results. So those people listed in the "DNA Connections" panel on the right-hand side of ancestor profiles are not DNA matches...they're suggestions for further investigation. They're populated when a WikiTreer enters on his or her own profile that a DNA test has been taken, and then nightly the system looks to see which profiles in the tree show a paper-trail connection to that person. If the connection and the type of DNA test taken are both appropriate (e.g., a male line direct ancestor and yDNA), the test-taker is listed in that "DNA Connections" section.