The desire to self-improve is probably as old as humanity: most of us want to be smarter, more athletic, more beautiful, or more talented. However, in the light of an ever increasing array of possibilities to enhance our capacities, clarity about the purpose and goal of such efforts becomes crucial. This is especially true when decisions are made for children, who are exposed to their parents’ plans and desires for them under a notion of increasing wellbeing. In recent years, cognitive enhancement has become a popular candidate for the promotion of wellbeing; welfarists even impose a moral duty on parents to cognitively enhance their children for the sake of their wellbeing. In this article, I aim to show that welfarists are mistaken in inferring such a moral obligation from the potential benefit of cognitive enhancement. In support of this, I offer three arguments: (a) the vagueness of wellbeing as a theoretical concept means it becomes impossible to apply in practice; (b) the link between cognition and wellbeing is far from unequivocal; and (c) quantification issues with regard to cognition make a duty impossible to discharge. In conclusion, I reject the welfarist approach as a justification for a parental moral obligation to cognitively enhance children.