Motivated by Cao et al. (2015), we utilize China’s one-child policy reform as a unique and exogenous setting to examine the economic impact of a potential rise in bequest motives among family firms, which is driven by the prospect of family and clanship expansion after the reform. A bequest motive is the economic incentive to accumulate wealth presently for inheritance by heirs in the future. It causes short-term present economic decisions to be influenced by long-term future utility expectations. On the one hand, the reform may strengthen stewardship as a means to maximize firm value for present family wealth enhancement and future inter-generational succession. On the other hand, the reform may weaken innovation and competitiveness by inducing reluctance against takeovers or outsider succession. Consistent with a positive economic impact, we observe that family firms experience (i) favorable ex-ante market reactions to the news of the reform and (ii) ex-post decline in managerial expropriation through tunneling after the reform. These findings of ex-ante investor anticipation and ex-post real effect are both stronger among less transparent family firms where Type-II agency problems are likely to be more pronounced. Further analyses also provide supportive evidence of a post-reform rise in the long-term value, measured by Tobin’s Q, and a decline in stock-selling by controlling shareholders among family firms. Our combined findings imply that this reform could induce positive externality on family firm governance.