In this paper, we present the first stage of an empirical bioethics project exploring the moral sources of paternal responsibilities and rights. In doing so, we present both (1) data on men's normative constructions of fatherhood and (2) the first of a two-stage methodological approach to empirical bioethics. Using data gathered from 12 focus groups run with UK men who have had a variety of different fathering experiences (n= 50), we examine men's perspectives on how paternal responsibilities and rights are generated and the significance of the genetic connection within the father–child relationship. We do not attempt to explore men's experiences of fatherhood or their fathering practices; and neither is the analysis driven from a particular sociological perspective. Rather, we explore men's normative constructions of fatherhood in order to present accessible data that might be of significance to the philosophical/moral debate on the sources of paternal rights and responsibilities.