Using a unique Chinese survey of parents and adult children, this paper examines how married children negotiate with their spouses for time devoted to caring for their own parents. Applying a collective bargaining framework, I show that the sex ratio at marriage shifts household bargaining in favour of the husband's parents when women are less scarce, or against his parents when women are scarcer. Such changing dynamics in the family may potentially reverse the current preference for sons in China, implying that those with sons, rather than daughters, may be increasingly in need of state support.