We have 2 types of immune systems: Innate and Acquired.
The innate immune system develops during the neonatal period together with the digestive system. This is why the health of the mother (physical, emotional and spiritual) is so important for the baby.
The acquired immune system is adaptive. The child slowly tries to develop immunity against toxins, bugs etc. This is natural vaccination (it is not natural to be exposed to 5 types of medical vaccinations at one time). This is why it is good for children to be exposed to low dose of various natural stress factors – bugs, dog and cat hairs, sunlight, cold water, dust etc. and not to live in a ‘sterile’ environment. A big family with many brothers and sisters also help in building immune health. This whole concept is called hormesis.
However, my advise is to stay away from artificial toxins – mobile phones, radiation and chemicals.
How did you deal with them when they fall sick as a result of these exposures? You treat them naturally with herbs, diet, fasting etc. The more you deal with them this way, the more they will increase their resistance to diseases. For example, it is known that children with frequent fever has less allergies in later life (provided they are treated naturally).