This paper proposes a reflection on the process of constructing a gender research problem by a doctoral student in education who comes from an undergraduate background in physics. Although with some experience in physics education, this is the first time the author approaches a research problem focused on education and especially on gender studies: the problem of the gender gap in physics education. The specific perspectives that the author possess are considered as the guide to the criterion by which the sources considered in defining the research problem were chosen. The guiding thread of the problematization process is the analysis of the Programme for International Student Asessment reports published by the Organisation for Economic Co-operation and Development regarding the mathematical proficiency of students in schools in countries participating in the data collections. Characterizing the framework provided by the Programme for International Student Asessment data, we introduce a theoretical tool, the identity lens, that can drop into specific cultural contexts and frame the gender biases involved in physics learning/teaching processes, reshaping the complexity of the gap. It is intended to support the idea that research in this area must necessarily take on a multi-perspective and intersectional character that does not risk falling into essentialism and male-female binarism.