Research on variability in software artefacts is something which is already studied extensively in research. The visualisation of variability is one aspect of this research, and results like e.g. feature diagrams are well-known and well-spread. When it concerns the origin of the variability within the phase of requirements engineering, research is much scarcer. A visualisation technique for both representing the origin and the amount of variability in requirements is not readily available in research. This paper provides a way to represent the origin of variability in requirements with the aid of a technique called formal concept analysis (FCA). Additionally the support that FCA can provide for variability related decisions during (early) requirements engineering is also depicted in this paper. Proof of the usability of FCA for the visualization, and documentation, of variability is shown with the aid of a real-life case study. FCA is also applied in the real-life case study to check the compatibility of FCA as a visualization method to support variability decision making during requirements engineering.