Yes / Shaping one's professional identity is a complex process that starts early on in the professional career and is influenced by many factors along the way. An important process in professional identity formation is professional imprinting. In socialization theory, professional imprinting refers to how individuals adjust behavior and beliefs to fulfill expectations from their working environments and achieve a feeling of belonging during sensitive periods. In this study, we turn to the academic setting, which is characterized by high researcher identity heterogeneity and thus can give us insights into the dynamics of professional identity development. Professional imprints during doctoral training lead to permanent characteristics in one's researcher identity. To investigate professional imprinting and its mechanisms, we conducted a qualitative study involving interviews with 16 PhD students and their supervisors (16 professors and 4 post-docs) within the setting of an EU-funded project. We identify the imprinting mechanisms that shape a researcher's identity during a sensitive period. Our study offers valuable insights for managers and policy makers about the role of supervisors or supervising managers in the development of the professional identities of junior colleagues and about the future career trajectories of people entering academia and industry.