Did he have an innate predisposition to react differently?
Not everyone has the genetic predisposition toward the development of allergy antibody immune responses to sensitizing agents, or allergens.
A family history of cardiovascular defects might suggest a genetic predisposition to the disease.
There is not thought to be a single cause of substance abuse, though scientists are as of 2004 increasingly convinced that certain people possess a genetic predisposition which can affect the development of addictive behaviors.
Evidence of a genetic predisposition for shyness is found in parents and grandparents of shy infants who report childhood shyness more often than relatives of children who are not shy.