From "Law and Order" to "CSI," not to mention real life, investigators have used fingerprints as the gold standard for linking criminals to a crime. But if a perpetrator leaves prints from different fingers in two different crime scenes, these scenes are very difficult to link, and the trace can go cold.
Ok, so caveat: this trivia is a few decades old in my head… but I thought there was a higher chance of similar fingerprints if there’s a genetic relationship? Which meant that mistaken identities were more common because of socio-economic and geographic factors for relations.