This article studies the emergence of cultural homogeneity in personal norms when the behavior of heterogeneous individuals is driven both by economic incentives and by personal norms. Agents participate in a team production game by choosing their level of costly effort. Norms evolve along the life cycle of the individuals according to two psychological forces: cognitive dissonance or consistency and informational conformity. The model sheds light on how primitive economic and behavioral parameters such as the distribution of skills, the income distribution, and the levels of materialism, conformism, and consistency in the group determine the long-run culture and its degree of cultural homogeneity.