Standpoint theory draws our attention toward how researchers' identities shape the production of knowledge. Their standpoint depends on previous experiences and their sense of identity, as well as on their social position relative to research participants and their communities. This is particularly the case in Participatory Design (PD), which entices researchers to develop personal relationships with participants through design. However, the way identities affect Participatory Design with children has so far been neglected in research, even though previous works focus on children's and researchers' roles in the design process or encourages auto-ethnography. In this paper, we build on case studies of how identities as they relate to gender and disability shape relationships between researchers and marginalised children through Participatory Design. We show how these identities are continuously negotiated throughout the design process, and how they shape outcomes. We close by proposing an approach to systematic reflexivity on identity in participatory design.