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Recent observations of pre-main sequence stars suggest that all stars may form in multiple systems. However, in the Galactic field only about 50 per cent of all systems are binary stars. We investigate the hypothesis that stars form in aggregates of binary systems and that the dynamical evolution of these aggregates leads to the observed properties of binary stars in the Galactic field. A thorough analysis of star count data implies that the initial stellar mass function rises monotonically with decreasing mass and that it can be approximated by three power law segments. Together with our assumption that the birth mass-ratio distribution is not correlated this leads to a contradiction with the distribution of secondary masses in Galactic field binaries with G-dwarf primaries which have too few low-mass companions. For the inverse dynamical population synthesis we assume that the initial distribution of periods is flat in log 10 P , where P is the orbital period in days, and 3 ≤log 10 P ≤ 7.5. This is consistent with pre-main sequence data. We distribute N bin = 200 binaries in aggregates with half mass radii 0.077 ≤ R 0.5 ≤ 2.53 pc, corresponding to the range from tightly clustered to isolated star formation, and follow the subsequent evolution of the stellar systems by direct N-body integration. We find that hardening and softening of binary systems do not significantly increase the number of orbits with log 10 P < 3 and log 10 P > 7.5, respectively. After the cluster with R 0.5 ≈ 0.8 pc disintegrates we obtain a population which consists of about 60 per cent binary systems with a period distribution for log 10 P > 4 as is observed and in which the G-dwarf binaries have a mass ratio distribution which agrees with the observed distribution. This result indicates that the majority of Galactic field stars may originate from a clustered star formation mode, characterised by the dominant mode cluster which has initially (N bin , R 0.5) ≈ (200, 0.8 pc). We invert the orbit depletion function and obtain an approximation to the initial binary star period distribution for star formation in the dominant mode cluster. Comparison with the measured distribution of orbits for pre-main sequence stars formed in the distributed mode of star formation suggests that the initial distribution of binary star orbits may not depend on the star formation environment. If a different stellar …