Daughter Centrioles Are Not Chemical Copies of Their Mothers: Geometric Persistence as a Replicative‐Age Counter

The daughter centriole is often described as a chemical copy of its mother: a daughter that survives beyond one cell cycle is said to acquire, through maturation, the same molecular constitution as the mother that templated it. This description is incomplete and, in one respect, wrong. A daughter centriole is assembled as a new organelle adjacent to the mother-a template-dependent neoassembly, not a molecular copy-and its geometry is imposed at that point by the local geometry of the templating mother and the surrounding module, without a dedicated proofreading step. This is distinct from de novo centriole biogenesis, which in the field denotes assembly in the absence of any pre-existing centriole. Because no error-correction mechanism restores a standard ninefold geometry, geometric modifications present in a mother are copied onto her daughters and persist and accumulate across successive divisions. The daughter is therefore not a chemical copy at birth, and mother-daughter divergence grows with each inheritance event. We formalise this claim as a testable model with pre-registered structural metrics measured by expansion microscopy on the persistent wall, the inner scaffold, and the appendage rings, and ask whether this geometric persistence could act as a replicative-age counter-a physical record of how many divisions a lineage has undergone. No primary centriolar data are presented; the contribution is a falsifiable framework and a low-threshold protocol.