Just my thoughts...I am starting to think that a "virus" is actually a parasite that we are getting through either the food, vaccines, or hate to say it but in the air.."chem trails"...I know that it sounds crazy....but the human body is desgined to fight...its called the immune system...ok...so could they be weakening it over time through the foods, vaccines, air..ect ect...so that some get sick and others don't..like cancer or ms or any other illness..it's like it gets activated. Which brings me to the part that nothing is hereditary....that its all "man made".