2.2. Etiological factors of atopic disorders

It is known that both environmental and genetic factors play a role in the etiology of atopic disorders (Konsensuslausuma 1998). If an atopic allergy is present in both parents, the probability for their children to have some kind of atopic disorder is 60%–80%, but if only one of the parents is suffering from atopy, the corresponding probability is 30%–50%. If neither of the parents have an atopic phenotype, the probability for their children to have an atopic allergy is only 15% (Savolainen 2001). In different populations, different possible candidate genes, which might have some connections with atopic disorders, have been found. Thus, it is obvious that atopic allergy is a genetically heterogeneous disorder (Konsensuslausuma 1998, Laitinen et al. 2000b, Savolainen 2001).

It is not definitely known, what exactly are those environmental factors, which determine whether a person develops an atopic allergy or not (Konsensuslausuma 1998). On the other hand, in addition to living in a farm environment during childhood/being a farmer’s child (Kilpeläinen et al. 2000, Pekkanen et al. 2001b), also a low socioeconomical status of the family (Williams et al. 1994), high number of children in a family/mother’s high parity (Strachan 1989, Pekkanen et al. 2001b), and an anthroposophic (Greek: wisdom about man; people who follow an anthroposophic way of life use antibiotics restrictively, have few vaccinations, and their diet usually contains live lactobacilli, which may affect the intestinal microflora) lifestyle of the family (Alm et al. 1999) have been found to be associated with a decreased risk of atopic allergies (Savolainen 2001, Hannuksela 2002).