In this paper, we construct a simple model that simultaneously produces inter cultural heterogeneity, distinct cultural signatures, and intra cultural heterogeneity. Our model assumes only that people pursue both consistency and conformity. We show that these two incentives produce distinct, diverse cultures but because they partially work at cross purposes they do not lead to fast intra cultural convergence. When we increase the relative strength of one of the forces, we exacerbate this tension. In an expanded version of the model that allows for errors, or what could be considered occasional idiosyncratic behavior, we find that small amounts of error result in substantial intra cultural differences. This result arises even though each force acting alone produces only moderate levels of intra cultural heterogeneity, thereby revealing the pitfalls of studying individual forces in isolation and extrapolating to their combined effects. Though here we apply our model to cultures, we could equally well apply some of its implications to other organized groups, including firms and political parties.