Environmental factors may interact with characteristics of the child. For example, parenting variables have less effect on the conduct problems of children with callous–unemotional traits than on those of children without these traits.59 In addition, the low degree of stress reactivity seen in youth with callous–unemotional traits may reduce the negative effects of exposure to adversities that predict heightened amygdala responses to threat,60,61 anxiety,62 and reactive aggression.39
