When I initially took my AncestryDNA test, a year or two ago, it said it could match with relatively good confidence genetic matches up to 6th cousins. I had hoped Mary and I would match, but we did not. That is not to say that we are not related. Oh we are but due to the recombinant nature of DNA she and I do not share the same sequence of DNA proteins from Jacob or Rebecca.
Since I took my test I have had several of my close relatives also take the test. It helps to both widen and deepen the pool from which to discover connections. So far, my dad, my sister, half-sister, two uncles, and two second cousins have taken the AncestryDNA test. Today the results came in for my Uncle Thomas and for the first time the results show that Cousin Mary and Uncle Thomas have a DNA match!
Now really all that does is scientifically confirm what Cousin Mary and I already knew. We're cousins! But oh, it's exciting to see one's research confirmed.