Although allergies have a genetic component, evidence strongly suggests that environmental factors play a major role in their recently increased incidence. Studies have shown that the incidence of allergies increases among immigrants who move from developing nations to the industrialized West. Additionally, a study of inhabitants of the former East Germany suggests that there may also be significant increases in allergy rates in areas where Western-style modernization takes place. One explanation for these increases is an increased exposure to unfamiliar allergens, such as dust mites, resulting from certain features of Western-style living, such as thick carpeting and the reduced airflow in well-insulated buildings. Yet, as Hamilton points out, allergy rates have continued to rise among populations long accustomed to such environments.