Previous research on bifurcation bias suggests that family firms generally provide preferential treatment to family members over non-family member. In reality, many family firms provide equal or more favorable treatment to non-family members. Based on the “ability-willingness” framework, this paper argues that existing literature predominantly focuses on the willingness of controlling families, while paying insufficient attention to their ability to engage in family-oriented particularistic behavior and the interactive mechanisms between ability and willingness. This oversight has led to contradictions between theory and practice. Therefore, using a sample of China’s listed manufacturing family firms from 2010 to 2019, this paper employs Fuzzy-set Qualitative Comparative Analysis (fsQCA) to investigate how the configuration of six antecedent conditions—family control, external supervision, market competition, kinship relationships, intergenerational succession, and family firm legitimacy—shapes bifurcation bias. The study reveals that: (1) A high level of bifurcation bias is driven by three configurations: “ability-willingness dual-high dominant type”, “willingness-ability complementary type”, and “ability-willingness collaborative type”. (2) A non-high level of bifurcation bias is associated with two configurations: “ability-willingness dual-low constrained type” and “ability-willingness disjointed type”. This paper reveals the configuration of bifurcation bias, thereby extending the theoretical boundaries of bifurcation bias and providing actionable guidance for balancing the family and firm systems.