This PhD project aims to investigate epigenetics research in the making, in order to understand how, where and why the new epigenetic knowledge is produced and identify the elements influencing the production of this emerging body of knowledge. More particularly, I will analyse the epigenetic notion of environment, by unpacking what it means in specific cases. Specifically, the project will entail: 1. A literature analysis: I will carry out both a systematic review of published epigenetics research to examine how the notion of environment is understood and defined in the literature and a systematic review of the social science literature to understand to what extent the notion of environment is critically reflected on. 2. Fieldwork: I will explore how the notion of environment is conceptualised and enacted in two case studies using ethnographic methods: breast cancer epigenetics and the EpiTwin project looking at diabetes. 3. Analysis: I will carry out a narrative analysis of the data collected during fieldwork in order to explore how researchers in epigenetics make sense of their world and understand the notion of environment in their professional lives.