Variation in the unresolved binary fraction with the mass of the primary star for all detected binaries (red) and for high mass-ratio binaries alone (q ≥ 0.6; blue). The fit provided by Arenou (2011), our Eq. (1), to the observed variation in the field is overplotted by the dashed black line. The shaded region corresponds to the masses ≤0.6M_⊙, wherein the binary fractions are expected to be spuriously inflated due to colour deviations of the observed Gaia DR3 photometry from the PARSEC isochrones.