  We consider the implications of a shared production mechanism between the
baryon asymmetry of the universe and the relic abundance of dark matter, that
does not result in matching asymmetries. We present a simple model within a two
sector leptogenesis framework, in which right handed sterile neutrinos decay
out of equilibrium to both the Standard Model and the dark sector, generating
an asymmetry in one and populating the other. This realization naturally
accommodates light dark matter in the keV mass scale and above. Interactions in
the dark sector may or may not cause the sector to thermalize, leading to
interesting phenomenological implications, including hot, warm or cold thermal
relic dark matter, while evading cosmological constraints. Under minimal
assumptions the model provides a novel non-thermal production mechanism for
sterile neutrino dark matter and predicts indirect detection signatures which
may address the unexplained 3.5 keV line observed in various galaxy clusters.
