Most parents know that children can come into the world with very different temperaments, in-born behavioral and emotional response tendencies that emerge early in life and tend to remain stable throughout the lifespan. Some children are easy-going from day one; they tend to respond positively to new things, adapt easily to their environment, and generally “go with the flow.” Other children are difficult and not very adaptable to change; they may present as more irritable and more negative. Still others are emotionally reactive; or shy and inhibited; or extremely active, impulsive, and “on the go.” These tendencies often become apparent in toddlerhood and tend to persist to some degree, eventually putting a stamp on an individual’s personality. Important dimensions of temperament include reactivity, tendency to approach or withdraw in the face of novelty, and ability to self-regulate (Calkins and Howse 2004), which as we saw in Chap. 2 is so important for successful illness management in later childhood and adolescence.

Temperament is relatively stable, with early child temperament predicting both internalizing and externalizing behavioral disorders later in development (e.g., Hinshaw 2008). Studies have shown that between 20–60 % of variance in temperament is due to genetic influences (Saudino 2005). At the same time, environmental factors—especially parenting—also play a powerful role in shaping these behavioral tendencies. The influence between parenting and temperament is bidirectional, with parenting moderating child temperament, and differences in temperament eliciting different parenting styles (Kiff et al. 2011). Temperament also moderates the effects of environmental stress (Schermerhorn et al. 2013) and parental psychopathology (Jessee et al. 2012) on child behavior. Recent theories go further to suggest that some children may be more susceptible to environmental influences (including parenting) than others (e.g., Belsky and Pluess 2009; Boyce and Ellis 2005), such that more sensitive or reactive children may benefit more from positive parenting but suffer more from ineffective or negative parenting.

It is therefore not surprising that temperament can greatly influence parent-child interactions around adherence. Children who are temperamentally more difficult, fearful, or reactive may resist complying with parent requests to cooperate with illness management. They may respond with avoidance or tears or tantrums, making management “a battleground … [that] will require significant emotional stamina by the parent” (Anderson and Schwartz 2014). In contrast, other children may adapt easily to the changes and challenges posed by adhering to a medical regimen. It is important to recognize that these individual differences in response and reactivity are part of each child’s biological inheritance, which can help explain in part why adherence is so difficult for some children but not for others.

Young children lack the abilities and the maturity needed to manage a chronic illness . It goes without saying that illness management in early childhood is the complete responsibility of the parent; the child’s role is to comply and cooperate. Gaining this cooperation, however, can prove quite challenging at times.