Understanding Non-Paternity Events

A non-paternity event (NPE) occurs when the recorded parent of a child is not the biological parent. DNA testing often reveals these situations when expected cousins or other relatives do not appear among your matches.

The app looks for missing or unexpected match patterns, as described in our triangulation guide. Clusters of matches that do not align with any known branch — or segments that triangulate to a completely different ancestor — trigger a Potential NPE detected message.

We highlight these cases using techniques from the DNA triangulation document: checking for the absence of expected matches, grouping your matches into clusters, and verifying shared segments through triangulation. When all evidence points to an unknown line, the system flags it so you can investigate further.

For a deeper dive into how triangulation works, see our triangulation overview.