Inequality in wealth is a pressing concern in many contemporary societies, where it has been show to co-occur with political polarization and policy volatility, however its causes are unclear. Here we demonstrate that inequality can covary reliably with other cooperative behavior, despite a lack of exogenous cause or deliberation. Under simulated cultural evolution via social learning selecting for trust and cooperative exchange, we find both cooperation and inequality to be more prevalent in contexts where the same agents play both the roles of the trusting investor and the trusted investee, in contrast to conditions where roles are divided between subpopulations. Cooperation is more likely in contexts of high transparency about potential partners and with a high amount of partner choice; while inequality is more likely with high information but no choice in partners. Our approach holds promise for examining the causality and social contexts underlying shifts in income inequality.