With my cat Sam as she gets older she gets a few more white hairs here and there on her black fur, never black hairs on the white areas! Tuxes are colored as tuxes from kittenhood on up to adulthood with just the occasional few white hairs mixed in as they age. I have been visiting tux kitties at the local humane society and they are clearly marked as tuxes at Basil's age. I think it makes him a little more unique as opposed to generic.