Contrary to mainstream opinion there was no clear link between susceptibility to allergens [i.e. Atopy] and asthma rates. Instead it was found that prevalence of atopy was uniform regardless of asthma rates. Interpretations include the strong possibility that there is an [unidentified] environmental cause of atopy.
Evidence from:
R Ronchetti et al. Int Arch Allergy Immunol (2007) Vol.142 p 79–85
“The Prevalence of Atopy in Asthmatic Children Correlates Strictly with the Prevalence of Atopy among Nonasthmatic Children”
Further detail: