Do some guinea pigs have sensitive skin?

I have 14 guinea pigs. Two of the adults are almost pure white abyssinians and I also have a white 2 week old baby with 3 dark colored litter mates. All three of the white piggies seem to scratch a lot while the dark colored ones don't seem to be bothered by itching at all. I'm wondering if my white guineas might have more sensitive skin than the others, and what I might do to offer some relief from the itching?