Kittens outside can pick up a number of very contagious viruses, and panleukopenia is deadly to them if they have not had any vaccinations. Kittens should have at least two FVRCP shots to prevent this, first shot at 8 weeks, and the second a month later. I sure hope that you reconsider the hazards these kittens face being outdoors. Coyotes, and fox could kill them without your even knowing they're gone. And as already mentioned, cars, dogs, poison....not a nice way to die. And there's a very good chance their mother is deaf (being blue eyed and white) and this could be the reason for her behaviour. I really hope you got the mom spayed when she went into the vets or she'll be pregnant again in no time, and homes are hard to come by since the hurricane hit down South. Kittens should not live outdoors IMO!