The emerging cosmological picture is of a spatially flat universe composed predominantly of three components : ordinary baryons ( \Omega _ { B } \approx 0.05 ) , non-baryonic dark matter ( \Omega _ { Dark } \approx 0.22 ) and dark energy ( \Omega _ { \Lambda } \approx 0.7 ) .
We recently proposed that ordinary matter was synthesised from mirror matter , motivated by the argument that the observed similarity of \Omega _ { B } and \Omega _ { Dark } 
suggests an underlying similarity between the fundamental properties of ordinary and dark matter particles .
In this paper we generalise the previous analysis by considering a wider class of effective operators that non-gravitationally couple the ordinary and mirror sectors .
We find that while all considered operators imply \Omega _ { Dark } = few \times \Omega _ { B } , only a subset quantitatively reproduce the observed ratio \Omega _ { B } / \Omega _ { Dark } \approx 0.20 .
The \sim 1 eV mass scale induced through these operators hints at a connection with neutrino oscillation physics .