The most likely explanation could involve the `` hygiene hypothesis , '' which suggests that improved sanitation methods and efforts to keep germs at bay may deprive young , still-developing immune systems from being trained to recognize and react appropriately to the right types of irritants . The U.S. environment seems to play some role in the allergy trend . ' I think it is a combination of many things that are going on. Parental behaviors and cultural practices may also play a role .
The U.S. environment seems to play some role in the allergy trend . ' I think it is a combination of many things that are going on. Parental behaviors and cultural practices may also play a role .