Original article
Generalising the Cinderella Effect to unintentional childhood fatalities

https://doi.org/10.1016/j.evolhumbehav.2005.10.001Get rights and content

Abstract

We investigated whether the repeatedly demonstrated increase in risk of child abuse and infanticide associated with living with a step parent generalized to cases of unintentional childhood fatal injury, the most common cause of death in children across the developed world. Reports were drawn from the Australian National Coroners' Information System (NCIS) on all cases of intentionally (n=32) and unintentionally (n=319) produced fatal injury in children aged under 5 years between 2000 and 2003. Even when using the most conservative possible analytic approach, in which all cases in which family type was unclear were classified as being from an ‘intact biological family’, step children under 5 years of age were found to be at significantly increased risk of unintentional fatal injury of any type, and of drowning in particular. Children from single-parented families were generally not found to be at significantly increased risk of intentional or unintentional fatal injury, while children who lived with neither of their biological parents were at greatest risk overall for fatal injury of any type.

Introduction

Over the last 25 years, Daly & Wilson, 1980, Daly & Wilson, 2001 and others (e.g., Flinn, 1988, Kim & Ko, 1990, Strang, 1993) have produced a body of work that has demonstrated repeatedly that, relative to children living with both biological parents, step children are at dramatically increased epidemiologic risk of being the victims of physical abuse and homicide. The phenomenon has often been referred to as the Cinderella Effect (Daly & Wilson, 1998). Daly and Wilson (1998) have argued that the Cinderella Effect is underpinned by the fact that the evolved parental psychological mechanisms that promote nurturing and protective behaviors in biological parents towards their young are only partially, if at all, activated in step parents. As such, higher rates of physical abuse by step parents are seen to be related to the fact that they are placed in the parental role without the same intrinsic level of commitment to the child's well being and tolerance for the inevitable and, often, substantial challenges of parenthood.

Of course, children do not just depend on their parents to do them no harm, but also to actively protect them from the many and varied dangers that are entailed in the complex physical and social environments that they inhabit. Accidental, or unintentional injury, which is about seven times more common than interpersonal violence as a cause of childhood fatality, is also the leading cause of death and disability in children across the developed world (UNICEF, 2001). Major causes of unintentional injury in children include road accidents, drowning, poisoning, falls, suffocation, and burns. As is the case with child homicide, death rates from injuries are considerably higher for infants (0–1 years) and young children (1–4 years) than for any other age group (Al-Yaman, Bryant, & Sargeant, 2002).

Parental supervision has been implicated as a fundamental contributing factor in the prevalence of unintentional childhood injuries (Peterson & Stern, 1997, Wills et al., 1997). Given that fatal accidents in childhood are unlikely to be an exclusively modern phenomenon, it is assumed that selective pressures would have favoured parental psychological sets that included propensities towards vigilance against such threats to the well-being of offspring. It would follow from theory of discriminative parental solicitude (Daly & Wilson, 1980) that such propensities would not be engaged to the same extent in step parents and, therefore, that step children may be at greater risk of morbidity and mortality from unintentionally produced injury.

While there have been studies that link family structure with some of the lesser forms of unintentional injury (O'Connor et al., 2000, Wadsworth et al., 1983), there are no studies that we are aware of that have looked at childhood fatalities. Thus, in order to investigate whether the Cinderella Effect generalized to cases of unintentional childhood fatalities, we collected data from the Australian National Coroner's Information System (NCIS), which is an Internet accessible database of all coroners' files from all states and territories across Australia. We examined cases of both intentionally and unintentionally inflicted fatal injuries for overrepresentation of children from single- and step-parented families, as well as for children who lived with neither biological parent. Given that drowning is arguably the most clearly supervision related of unintentional deaths in children (Peterson & Stern, 1997), we also analysed cases of drowning separately in order to more specifically test the reduced vigilance hypothesis.

Section snippets

Participants

Data obtained from the NCIS included cases from all state coroner jurisdictions within Australia except for Western Australia. Access to Western Australian data was subject to additional procedural requirements that, for practical reasons, were not pursued. Thirty-two cases of intentionally produced fatal injury cases in children under 5 years of age were sampled from the NCIS online database. The sample consisted of 12 female and 20 male children with a mean age of 1.47 years (S.D.=1.32) at

Results

Calculation of odds ratios was based on population estimates obtained from the Family Characteristics Australia survey (ABS, 2003). The numbers of child fatalities that fell into each cell (family type by fatality type) are presented in Table 1, along with the ABS estimate of the number of children under the age of 5 years from the Australian population who fall into each family type category.

Odds ratios calculated for each family type and fatality category are presented in Table 2. Odds ratios

Discussion

These results indicate that the repeatedly reported increase in risk of being a victim of fatal child abuse associated with having a step parent generalises to cases of unintentional fatality. Odds ratio calculations for intentional abuse fatalities are comparable to those found in previous studies in the area (Daly and Wilson, 1998) and reaffirm the much-repeated finding that step parenthood is a substantial risk factor for child homicide in preschool-aged children. The figures for

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