Social transmission is conformist, variation is guided, variance is proportional

While cultural evolution has matured into a fully-fledged field, the science of cultural transmission remains underdeveloped. Most existing models still rely on naive assumptions of discrete trait imitation, while more complex transmission models for continuous traits are virtually non-existent. This paper fills the void by introducing a continuous transmission model that integrates biased transmission, conformity, and three distinct variance components into a single probability density function; one that still draws inspiration from the original biometric models that shaped early thinking about biological inheritance at the end of the 19th century. Participants played a trivia-style guessing game in an app, being exposed to the answers of previous participants (“cultural parents”) and providing numeric estimates (“cultural offspring”) that serve as a continuous heritable trait for analysis. This approach yields clear evidence for three key features long hypothesized to distinguish cultural from biological inheritance: people conform to majority input, aligning with mutually similar social cues; they systematically adjust their estimates toward the correct answer (guided variation); and their estimate variance is not constant, but scales with the variance of presented cues. All three effects can be reliably estimated within a single generative model.