The strong influences that siblings have on each other have been documented in the child development literature. With the onset of paediatric illness in one child within a family, changes are likely to occur in the healthy siblings' behaviors, moods, and relationships within the family. The changes are a result of not only the changes within the sibling relationships but also changes in family routines, allocation of parents' time and attention to each child, and the marital relationship. Although early research on sibling adjustment to paediatric cancer focused on the increased risk to maladjustment, other research has suggested positive responses such as increased social competence. Overall, the literature shows that there is considerable variability in sibling responses to paediatric cancer.