Cinderella Effect - Supportive Evidence

Supportive Evidence

Strong support for the Cinderella effect as described by Daly and Wilson comes from a study of unintentional childhood fatal injuries in Australia. Tooley et al. follow the argument of Daly and Wilson to extend the Cinderella effect from cases of abuse to incidences of unintentional fatalities. Children are not only vulnerable to abuse by their parents, but they are also dependent on their parents for supervision and protection from a variety of other harms. Given that parental supervision is fundamentally correlated to incidences of unintentional childhood injury as shown by Wadsworth et al. and Peterson & Stern, Tooley et al. posit that selective pressures would favor an inclination towards parental vigilance against threats to offspring well-being. Tooley et al. further argue that parental vigilance is not as highly engaged in stepparents as genetic parents, therefore placing stepchildren at greater risk for unintentional injury.

Based on data gathered from the Australia National Coroners’ Information System, stepchildren under five years of age are two to fifteen times more likely to experience an unintentional fatal injury, especially drowning, than genetic children. Additionally, the study finds that the risks of unintentional fatal injury are not significantly higher for genetic children in single parent homes versus two-parent homes. This difference suggests that removing one biological parent from the home does not significantly increase risk to the children, but that adding a nonbiological parent to the home results in a drastic increase in the risk of unintentional fatal injury. Despite the fact that adding a stepparent to the home increases the available resources in terms of supervision in comparison to a single-parent home, risk of unintentional fatal injury still significantly rises. This higher risk of injury for stepchildren can be attributed to the fact that stepparents occupy the same supervisory role as a genetic parent, yet they have a lower intrinsic commitment to protecting the child and therefore are less likely to be adequately vigilant. The authors conclude that the Cinderella effect applies not only to purposeful abuse by stepparents, but is also relevant to explaining increased rates of accidental fatalities among stepchildren.

Furthermore, a study of parental investment behaviors among American men living in Albuquerque, New Mexico reveals a trend of increasing financial expenditures on genetic offspring in comparison to step-offspring, which also suggests that parents are less inclined to preserve the well-being of stepchildren. The study assesses paternal investment based on four measures: the probability that a child attends college, the probability that the child receives money for college, the total money spent on children, and the amount of time per week spent with children. Four different classifications of father-child relationships are examined and compared, including fathers living with their genetic children and fathers living with the stepchildren of their current mates. Though the study finds a clear trend of increasing investment in genetic children, the data also shows that fathers do still invest substantially in stepchildren. The authors explain the parental investment exhibited by fathers towards stepchildren as possibly motivated by the potential to improve the quality or increase the duration of the man’s relationship with the stepchildren’s mother. This studied corroborates the findings of Lynn White, that stepparents in general provide less social support to stepchildren than their genetic children.

Though the general trend of the data from this study supports the Cinderella effect, Anderson and colleagues note that the observed differences between parental investment in genetic children and stepchildren might be slightly reduced by a few confounding factors. For example, the authors point out that stepparenting is a self-selective process, and that when all else is equal, men who bond with unrelated children are more likely to become stepfathers, a factor that is likely to be a confounding variable in efforts to study the Cinderella effect. Anderson and colleagues also conducted a similar study of Xhosa students in South Africa that analyzes the same four classifications of paternal-child relationships, and this study offers similar results to those observed among fathers in Albuquerque.

Additionally, a study of Hadza foragers in Tanzania by Marlowe also finds evidence of decreased care provided by fathers to stepchildren when compared with genetic children. The author uses the Mann-Whitney U-tests to evaluate most of the observed differences in care exhibited towards genetic and stepchildren, and finds that Hadza men spend less time with (U=96), communicate less with (U=94.5), nurture less, and never play with their stepchildren. Marlowe further argues that any care that is provided towards stepchildren is likely attributable to the man’s mating efforts and not parental interest in the well-being of the stepchildren.

In further support of the Cinderella effect as elaborated by Daly and Wilson, a study conducted in a rural village in Trinidad demonstrates that in households containing both genetic children and stepchildren, fathers devote approximately twice as much time to interaction with genetic offspring in comparison to stepchildren. Additionally, this study finds that the duration of the relationship between the stepfather and stepchildren is negatively correlated with the relative proportion of interaction time and positively correlated with the relative proportion of antagonistic interactions between the two. As a proportion of total time spent interacting with genetic and stepchildren, fathers are shown to have approximately 75 percent more antagonistic interactions with stepchildren. In this study, antagonistic interactions are defined as involving physical or verbal combat or an expression of injury. This includes, for example, spanking, screaming, crying, and arguing. The duration of the relationship between genetic fathers and children shows a positive correlation with both relative proportion of interaction time and antagonistic interaction. The author argues that these results show that in terms of time invested, fathers favor genetic children over stepchildren, and this preference is not attributable to the duration of the father-child relationship, a factor which is sometimes believed to be a confounding variable in the Cinderella effect. Though this study does claim a significant increase in antagonistic behavior between stepparents and stepchildren and therefore supports the Cinderella effect, it also notes that only six percent of all the observed parent-child interactions were considered antagonistic, and that the researchers never noticed any blatant physical child abuse.