Current ethical guidelines for the genetic testing of children protect thechild’s future autonomy’from parental choices if there is no immediate medical benefit from testing. Drawing loosely ongovernmentality’as an analytics of power, we argue that ethical guidelines are symptomatic of a shift in the way that children are constituted as subjects and as potential citizens. For instance, the concept of autonomy has emerged as a liberal solution for the governance of genetic information: subjects are to be governed through their freedom and by enacting their lives through an ethic of choice. However, governmentality is at risk of missing some important tensions within the politics of childhood testing if it fails to analyse the authoritarian dimension of liberalism. The paternalistic character of ethical governance is not so much a confrontation between autonomy and medical authority, but a new kind of obligation between professionals and clients. In this paper, we consult empirical examples of interview data with medical professionals to examine the rhetorical construction of ethical dilemmas. Professional accounts reveal competing versions of autonomy and ambivalence about difficult and challenging interactions with parents and children. Our findings suggest that authoritarian and liberal practices are twin aspects of a practical rationality that seek to recruit the child’s autonomy as a device for shaping adult decisions and producing future subjects who are self-sufficient in the management of their genetic risk.