Violence against Stepchildren: Evidence and Counterclaims

Martin Daly

    Parental investment is costly and evolves to be allocated where it is most likely to promote parental fitness.  Although it is implausible that abusing or killing stepchildren would have promoted the assailants’ fitness in ancestral human social environments, a general preference for their own offspring surely would have.  Elevated risks to stepchildren are a likely byproduct of such discriminative parental solicitude. 

    It is now almost 30 years since collaborators and I first demonstrated that children living with one genetic parent and one stepparent were indeed mistreated more than children in intact birth families.  Further research has shown that such “Cinderella effects” are widespread (perhaps universal), are often substantial, and cannot be explained away as artifacts of any correlated factor yet suggested.

    The disproportionate victimization of stepchildren is now the most extensively documented generalization in the family violence literature, raising further questions, such as what explains variation in risk differentials between maltreatment types and locales, and whether individual-level predictors of abuse are the same for genetic parents and stepparents.  Unfortunately, progress on these important issues has been hindered by a relentless distraction: the manufacture of “controversy” about whether Cinderella effects exist at all.  A motivation for this denial appears to be antipathy to the Darwinian worldview and/or to its application to Homo sapiens.