The most frustrating unknown father case I've ever worked is Midge (not her real name).  Midge has great matches!  I even know the town her biological father was from.  That's not the problem. The problem is that half the town are Smiths, they're all related, and Smithville's local pastime appears to be extramarital sex.  Of Midge's top three paternal matches at AncestryDNA, two have misattributed parentage events (MPEs).  The jury's still out on the fourth.  Her three top matches at 23andMe match one another as first cousins, but none of the trees overlap.  For all I know, none of their trees are biologically correct. There are so many MPEs in Midge's match lists, I created a custom label to remember who they are. Oh, and Midge's father was obviously born outside of wedlock, too! A silver lining of the endogamy is that Midge usually has secondary matches to her top matches that represent both sides of the matches' trees, so I can validate some of the pedigrees.  These are people who share a lot of DNA with the primary match but not much with Midge.  This is how I know so many of their trees are not biologically correct.  It's tedious work, though. Manual clustering has been a huge help, so I was eager to try out Ancestry's new custom clusters—available through Ancestry's Pro Tools package for an added fee—to nudge things along. Note to self:  Custom clusters are not meant for endogamy.  I know this.  A girl can dream. Manual ClusteringMy manual cluster includes descendants of Mack & Sarah Smith, a Smithville couple who had 10 children between 1885 and 1915.  One of those children was probably Midge's grandmother.1   The blue-shaded cM column shows shared DNA with Midge.  Matches in the upper left quadrant are all descendants of Teddy, a son of Mack & Sarah.  The group in the bottom right quadrant descend from three of their other children.  Shared centimorgan values between matches are above the diagonal and family relationships are below the diagonal.  (