The discussion over the roles of genes and environment on the phenotypical specification of organisms has held a central role in science philosophy since the late 19th century and has re‐emerged in today's debate over genetic determinism and developmental plasticity. In fin‐de‐siecle Vienna, this debate coincided with a philosophical debate over empiricism/materialism versus idealism/vitalism. Turn‐of‐the‐century Vienna's highly interdisciplinary environment was also the birthplace for the model system of the un‐opposed molar. The un‐opposed molar system features new tissue formation at the (...) roots of teeth and tooth drift once opposing teeth are lost. The un‐opposed molar model system was revived by a group of Viennese scientists who left Vienna during the Nazi period to address Vienna's questions about evolution and heredity and about genes and environment in Chicago's post‐WWII scientific exile community. Here we are using the colorful history of the un‐opposed molar to investigate the role of culture and method in the scientific evolution of a model system. BioEssays 29:819–830, 2007. © 2007 Wiley Periodicals, Inc. (shrink)