Why do Jews have to kitchens?

Answer 1

because in our bible it says that we shall not cook a lamb in his mothers milk, we perceived this as don't eat milk and meat together so to help us keep them separate we cook meat in one kitchen and milk in another.

another reason might be because of passover, on passover we cannot eat certain foods called chametz to make sure we don't eat it we use another kitchen or thoroughly clean out our original kitchen.