This paper overviews key empirical findings from social science research regarding the impact of gamete donation on child wellbeing. In particular, the paper addresses current regulatory debates concerning information sharing and the best interests of the child by considering psychosocial aspects of telling--or not telling--children about their donor conception and the identity of their donor. The paper identifies three core sets of empirical, ethical and policy concerns underpinning these debates relating to (i) the psychosocial impact of gamete donation per se on child wellbeing, (ii) the psychosocial impact of parental disclosure decisions on child wellbeing, and (iii) the psychosocial implications of donor identification for donor-conceived offspring. The paper illustrates how these concerns are framed by ideas about the significance-or not-of 'genetic relatedness'; ideas which have come to the fore in contemporary discussions about the potential consequences of donor-conceived individuals gaining access to their donor's identity. By drawing together research findings that may be pertinent to the regulation of gamete donation and information sharing, a further aim of this paper is to explore the potential use and misuse of empirical 'evidence' in ethical and policy debates. Whilst this paper starts from the premise that psychosocial data has a vital role in grounding normative discussions, it seeks to contribute to this dialogue by highlighting both the value and limitations of social science research. In particular, the paper argues for a cautious approach to applying psychosocial evidence to ethical issues that is sensitive to the caveats and nuances of research findings and the changing cultural and regulatory context.