Small RNA–mediated inheritance has emerged as a prominent mechanism by which regulatory states can be transmitted across generations without changes in DNA sequence. Studies in Caenorhabditis elegans show that such inheritance is tightly regulated in its duration, specificity, and reversibility. In this chapter, I examine the molecular logic underlying small RNA inheritance, emphasizing how RNA amplification, RNA modification, subcellular organization, and chromatin engagement interact to shape the lifetime of heritable silencing. Rather than viewing epigenetic inheritance as a parallel mode of heredity, the chapter highlights how RNA- and chromatin-based pathways actively constrain the persistence of regulatory states, enabling transient, conditional, or long-lasting memory depending on the context. Placing these mechanisms within an evolutionary framework, I propose that small RNA inheritance functions as a regulated buffering system that modulates the temporal gap between environmental or genomic perturbations and long-term fixation. This perspective underscores how selection can act on regulatory architectures that control the stabilization and erasure of epigenetic states, thereby shaping phenotypic variation across generations while preserving the central role of genetic context.