We have collated multiplicity data for five clusters ( Taurus , Chamaeleon I , Ophiuchus , IC348 , and the Orion Nebula Cluster ) .
We have applied the same mass ratio ( flux ratios of \Delta K \leq 2.5 ) and primary mass cuts ( \sim 0.1–3.0 M _ { \odot } ) to each cluster and therefore have directly comparable binary statistics for all five clusters in the separation range 62–620 au , and for Taurus , Chamaeleon I , and Ophiuchus in the range 18–830 au .
We find that the trend of decreasing binary fraction with cluster density is solely due to the high binary fraction of Taurus , the other clusters show no obvious trend over a factor of nearly 20 in density .

With N -body simulations we attempt to find a set of initial conditions that are able to reproduce the density , morphology and binary fractions of all five clusters .
Only an initially clumpy ( fractal ) distribution with an initial total binary fraction of 73 per cent ( 17 per cent in the range 62–620 au ) is able to reproduce all of the observations ( albeit not very satisfactorily ) .
Therefore , if star formation is universal the initial conditions must be clumpy and with a high ( but not 100 per cent ) binary fraction .
This could suggest that most stars , including M-dwarfs , form in binaries .