As neutrinos have mass, other masses should interact with them, however weakly, through gravitation.
In the classical atom we have protons and neutrons in the nucleus (save for protium), with electrons more peripherally, in 'orbits' unless through ionization they become free of their parent atoms.
Since neutrinos also derive from parent atoms, might we not be able to speculate that inherently they too are parts of atoms, though in their free form are all only gravitationally bound but so weakly as to only orbit gigantic concentrations of mass, such as entire galaxy clusters or even larger ones such as the cosmologist's 'Great Wall'?
Note that neutrinos, though they are typically translating through most solid matter (even entire planets) without interacting, occasionally do in fact interact with atomic nuclei, transforming them. So at least until such transformation is complete, they do in fact become a separate part of the target atom.
Just some thoughts.
Jess Tauber