We examine the role of vicinal surface steps in the formation and propagation of twins during the growth of epitaxial III-V thin films (GaAs, InP, GaSb, AlSb) on silicon substrates. This is achieved through the combined use of two-dimensional X-ray diffraction and conventional transmission electron microscopy techniques, which allow for both a macro and nano/micro characterization of the material systems. Observed is a systematic suppression of twins formed opposite to the tilt direction of vicinal substrates through a process of step-flow overgrowth of nucleated twins, and an enhancement of twins toward the tilt direction when the fastest growth planes are aligned with the step-flow. These results indicate a probable path to the enhancement of the electronic mobility of lateral devices based on III-V semiconductors on silicon.