• child care;
  • aggression;
  • externalizing behavior problems


In an intriguing account, the hypothesis is proposed that elevating effects of quantity of childcare on aggression might not, as other research has suggested, be dissipating over time, but instead be diffusing across groups of children. Paradoxically, this diffusion may also affect children with little or no experience with non-maternal care. If supported, this hypothesis may cause great concern about the increasing childcare use in western countries. In this commentary, we take a closer look at this hypothesis, focusing on limitations in ethnic and cultural diversity of the available data, on the inconclusive role of temperament, on the causal nature of some conclusions, and on the role of the father as a non-maternal caregiver.