This article introduces the notion of kinship surveillance as the unilateral production of knowledge about familial relationships of migrants, undertaken and weaponised by the state to enact border regimes. I ask why and how knowledge about migrants’ kinship relations has been rendered a relevant scale of border control, and how it has historically been enacted through different media technologies. The article’s aim is to expose the historical cultural work that legitimises a technopolitics of weaponisation around kinship: rendering an enunciation of “family” as biological and genetic into a means of enacting border regimes. In particular, the article unpicks how fears of fraud and deception, and fears of being “too slow” and “overwhelmed”, structure the ways kinship gets technologically reduced to information points that can be extracted, stored, surveilled, and used in complicity with border regimes. In doing so, the paper draws on archival material around the introduction of “DNA fingerprinting” by the UK Home Office during the 1980s, as well as on the case of blood group testing of Chinese immigrants employed by the USA in the 1950s. At a moment of rampant digitalisation and automation of evermore clamped-down border regimes, I argue that historicizing the technopolitics of kinship surveillance decentres innovationist hypes around “smart” border technologies and challenges the naturalised epistemic authority and weaponisation of knowing and surveilling migrants’ familial relations.