How do precision medicine initiatives (re)organize relations between individuals and populations? In this article, we investigate how the curation of national genomic populations enacts communities and, in so doing, constructs mutual obligation between individuals and the state. Drawing on ethnographic fieldwork in the Danish National Genome Center (DNGC), we show how members of advisory bodies negotiated the inclusion criteria for two different genomic populations: a patient genome population and an envisioned ‘Danish’ reference genome population. The patient genome population was curated through a politics of inclusion, of as many genomes as possible, whereas the reference genome was to be curated through a politics of exclusion, to include only the genomes of ‘ethnic’ Danes. These two data populations configure differently the community of ‘Danish patients’ who might benefit from precision medicine, and thereby prescribe different moral continuities between person, state, and territory. We argue that the DNGC’s patient genome population reinforces reciprocal relations of obligations and responsibility between the Danish welfare state and all individuals, while the proposed Danish reference genome population privileges the state’s commitment to individuals with biographical-territorial belonging to the nation-state. Drawing on scholarship on social and health citizenship, as well as data solidarity in the Nordics, the discussion shows how population curation in national precision medicine initiatives might both construct and stratify political obligation. Whereas STS scholarship has previously deconstructed the concept of ‘population’, in the context of the troubling and violent effects of the management of human populations, we point to the importance of population curation as a vehicle for making the individual legible as part of a community to which the state is responsible and for which it is committed to care.