well independently of what your position on moral realism vs non realism is, an explanation is not the same thing as a justification - that I can find an evolutionary basis for a behavior does not imply that that behavior is metaphysically good or whatever
speculating about what moral systems are the most evolutionarily advantageous, or what the evolutionary basis of moral systems are, is not a solution to is/ought, it does not even engage with it
idk exactly what you mean by grounded, but unless you solve is/ought, your preference is an animal preference caused by the series of events which led to your life, and is a natural phenomenon, not a metaphysical one
Thing is you can move past your own preference of course. I may perfer pizza, but its bad for me and so I don't eat it much. However if I never knew it was bad for me, my Pathos would obviously win out.
