["Topics in Cognitive Science, EarlyView. ", "\nAbstract\nThis study investigates the cultural transmission of mushroom knowledge through an iterated learning paradigm, focusing on how content‐based and model‐based biases shape transmission across generations. Norwegian participants, predominantly mycophobic, were arranged in seven linear transmission chains of eight generations each, interacting in dyads. A trained confederate provided initial information about 24 mushrooms regarding edibility (poisonous/edible/inedible), accompanying facts (death/survival/neutral), and the information source's familiarity (familiar/unfamiliar). Results revealed a strong bias toward labeling mushrooms as poisonous, reflecting cultural caution. Model‐based biases (familiarity) did not significantly influence transmission, while content‐based biases (fact type) affected early fidelity, especially survival‐related facts. Over generations, details beyond edibility were progressively lost, with transmission converging on simplified edibility judgments. This suggests cumulative cultural simplification prioritizing survival‐relevant information. These findings imply that cultural attitudes influence the transmission of high‐risk content, amplifying caution across generations. Despite limitations, this study offers novel empirical data on mushroom knowledge transmission in a mycophobic context and lays the groundwork for cross‐cultural comparisons with mycophilic societies.\n"]