Following the metaphorology of Hans Blumenberg, this paper reconstructs the metakinetics of the absolute metaphor of ‘plasticity’ across 19th and 20th century biological thinking, in order to provide a genealogy of current uses of this notion in the heterogeneous field of epigenetics. Our analogical comparison of historically distant theorizations of ‘plasticity’ allows identifying several typologies of the reciprocal entanglement of bodies, biologies and their (ecological, social, cultural) environments. Building upon this historico-epistemological analysis, the paper then looks at the novelty of the biosocial openings offered by epigenetic biosciences. By showing how metaphorical ways of knowing the plastic openness of bodies to their surroundings constituted also the conditions for norming and acting on the effects of social conditions on biology, the article concludes that traces of biosocial thinking run throughout the recent history of biology, and are thus far from being a distinctive opening of contemporary epigenetics.