Left panel: SFDs of the observed asteroid families. Middle panel: SFDs of 378 distinct synthetic families created during one of the collisional simulations of the MB and comets. Initially, all synthetic SFDs are very steep, in agreement with SPH simulations (Durda et al. 2007). We plot only the SFDs that fulfil the following criteria: D_PB ≥ 50 km, D_LF ≥ 10 km, LR/PB < 0.5 (i.e. catastrophic disruptions). Right panel: the evolved SFDs after comminution. Only a minority of families are observable now, since the number of remaining members larger than the observational limit D_limit ≃ 2 km is often much smaller than 100. The SFD that we use for the simulation in Sect. 10 is denoted by red.