I know that there does exist a mod for one of the Virtual Villagers games with all the peeps having darker skins. I'd imagine one of the modders might produce a similar one for VF2 if there were any demand. However, the hair of most people of colour is black or dark brown, while one of the attractions of VV/VF is the wide range of hair colours,which, incidentally, make it easier to tell the peeps apart.