That doesn't seem to be holding true today. Even kids with lower income backgrounds are more likely to get asthma. I agree with Dr. Rubin that we don't have much to go on. Some say it can be genetics, some say outdoor pollutants, and some indoor pollutants. Some even say ethnic and racial groups are predisposed to get asthma, like Latinos and African-Americans.
Children are vulnerable because of the size of their airway and their ability to fight disease.
Anatomically they have different predispositions to their disease compared to adults. There are also factors of detection, where parents may not be aware their children are wheezing and sick until a more advanced point in the course of their disease. Children can develop asthma that is related to respiratory illness and viruses, as well as environmental factors such as dust and influence of cockroaches and other environmental factors. So it's an issue of trying to get parents educated to very early symptoms of asthma, and at the same time to modify the environmental impact that children are faced with. For example, the family that's not aware that secondary tobacco smoke can set off or trigger an asthma attack needs to change their behavior so the child is not exposed to that tobacco smoke.