This paper explores competing discourses that envision different socio-technical landscapes opened up by the completion of the map of the human genome in 2003. It examines the ways in which the map, and it organising principle and very rationale--the gene as the sole or prime agent through which to understand the body and its disordering (as disease)--has been interpreted in quite distinct ways. It suggests how the sequences of a genomic map have post-genomic con-sequences that depend on a social rather than simply biological reading of genomic agency. Various accounts of the map and genetic agency or [sic] described, within science, science policy and social science, especially across science and technology studies (STS). The paper concludes with a comparative summary of these positions and asks whether a deconstructive reading of genomic agency by STS analysts might be the basis for a critical re-constructive engagement with post-genomic policy discourse that avoids the over-determination of agency one often finds in the latter.