  Cosmological simulations consistently predict specific properties of dark
matter halos, but these have not yet led to a physical understanding that is
generally accepted. This is especially true for the central regions of these
structures. Recently two major themes have emerged. In one, the dark matter
halo is primarily a result of the sequential accretion of primordial structure
(ie `Nature'); while in the other, dynamical relaxation (ie `Nurture')
dominates at least in the central regions. Some relaxation is however required
in either mechanism. In this paper we accept the recently established
scale-free sub-structure of halos as an essential part of both mechanisms.
Consequently; a simple model for the central relaxation based on a self-similar
cascade of tidal interactions, is contrasted with a model based on the
accretion of adiabatically self-similar, primordial structure. We conclude that
a weak form of this relaxation is present in the simulations, but that is
normally described as the radial orbit instability.
