We focus on the ethical tensions that shape disclosure choices in family-controlled enterprises, drawing upon the Behavioral Agency Model (BAM) and the socioemotional wealth (SEW) framework to examine how family firms’ biodiversity disclosure practices differ from those of non-family firms. Utilising a large longitudinal global dataset comprising 49,169 firm-year observations across 53 countries from 2007 to 2022, we find that family firms disclose significantly less biodiversity-related information compared to non-family firms. Our findings suggest that this negative association stems from their prioritisation of control and influence – a key SEW dimension – at the expense of biodiversity disclosure. Consistent with BAM, we find that family firms adjust biodiversity disclosures when SEW is at risk. Specifically, family firms located in biodiversity-sensitive locations or under greater analyst scrutiny tend to disclose more biodiversity information, suggesting that external contextual pressures shape their disclosure practices.. These findings highlight adaptive sustainability behaviours of family firms in response to both location-based and market-driven pressures. We contribute to business ethics, sustainability reporting, and family business research by showing how BAM and SEW dynamics shape biodiversity disclosure as an ethically charged aspect of sustainability reporting. Our study underscores the tension between family firms’ long-term orientation and their disclosure hesitancy, and demonstrates how external pressures, such as analyst scrutiny and biodiversity-sensitive environments, influence transparency decisions. Overall, our findings highlight the ethical and regulatory importance of advancing biodiversity disclosure, especially for family-controlled firms where socioemotional priorities may constrain transparency. By addressing endogeneity concerns through firm ownership transitions and validating our results across multiple robustness checks, we offer grounded insights with practical relevance for policymakers, investors, and sustainability advocates.