Really good immune system or what?

So both my parents had bronchitis for two weeks straight. They both stayed home from work. They were coughing and they had stomach problems and fevers and everything. Our house is very small. I didn't get as much as a fever. How is it possible that I didn't catch what they had? I mean i was around them while they coughed and i even hugged them too. Do I just have a great immune system? Im always drinking water and orange juice and eating healthy foods. I hardly eat fatty foods.