Martin Daly and Margo Wilson’s research into the clearly identified risks that stepparents pose to their stepchildren has led to some of the most influential and path-breaking insights to emerge in the past three decades in the field of human psychology and evolutionary psychology.
The two Canadian-born researchers found overwhelmingly powerful evidence globally that stepparenthood has “turned out to be the most powerful epidemiological risk factor for child abuse and child homicide yet known.”
What’s more, they conclude in their influential 2002 paper, The Cinderella Effect: Parental Discrimination Against Stepchildren (1), that “non-violent discrimination against stepchildren is substantial and ubiquitous.”
Daly and Wilson turn to the research done widely in non-human species on Darwinian selection. Under this model of “the selfish gene,” the care of dependent young will ordinarily be directed selectively toward close relatives of the caretaker.
Daly and Wilson write that “psychological adaptations that produce discriminative parental solicitude vary between species, in ways that reflect regularities in each species’ ancestral environment of evolutionary adaptiveness (EEA).”
According to Daly and Wilson, “there is nothing magical about parental discrimination: preferential treatment of one’s own young exists only where a species’ ecology demands it.” The two see no reason why the evolution of the human psyche would be excluded from this logic.
Daly and Wilson’s wealth of evidence
Daly and Wilson’s research provides clear epidemiological evidence, including the use of an archive of 87,789 validated reports of child maltreatment in the United States. They support their findings with dozens of peer-reviewed studies of stepparenting abuse across cultures that also find similar patterns of abuse and stress.
These findings have yet to be refuted in any serious peer-reviewed paper. They are constantly cited by critics, who fail to show any new evidence refuting their findings.
Daly and Wilson’s research also went well beyond lethal and abusive treatment of children by their non-genetic parents. The outcomes they list include show how medical care is restricted, education funding is withheld, and other forms of non-physical abuse and favoritism prevail. Some of the main findings include:
- In several countries, including Canada and the United States, stepparents beat very young children to death at per capita rates that are more than 100 times higher than the corresponding rates for genetic parents.
- Children under three years of age who lived with one genetic parent and one stepparent were estimated to be seven times as likely to be the victims of validated physical abuse as those living with both their genetic parents.
- In a Korean study of schoolchildren in the 3rd and 4th grades, 40 percent of those living with a stepparent and a genetic parent were reported to be “seriously battered” once a month or more, compared to 7 percent of those living with both their genetic parents.
- In Finland, 3.7 percent of 15-year-old girls living with a stepfather claimed that he had abused them sexually, compared to 0.2 percent of those living with their genetic fathers.
- Consistent findings of research show that stepparents and stepchildren alike rate their relationship as less close and less dependable emotionally and materially, and that all parties in stepfamilies are less satisfied, on average, than persons living in intact first families.
- Stepchildren suffer elevated rates of accidental injury, both lethal and nonlethal, from infancy onwards, likely because they are not monitored and protected as closely, and they experienced elevated mortality in general, not just from assaults.
- Research in the island of Dominica has shown that stepchildren have chronically elevated levels of the stress hormone cortisol, which is strongly associated with worse health outcomes in nearly all categories.
- Numerous American studies, controlled for parental means, have demonstrated that children living with stepmothers do not receive the same regular medical and dental care than children living with their genetic parents.
- Less money is spent on food in stepmother households.
- Fiscal support from families for higher education is substantially reduced for stepchildren, even when both parental wealth and the child’s scholastic record are statistically controlled.
Weighing the evidence, Daly and Wilson also note that most stepparents also find pleasure helping to raise the children of their partners, and that many stepchildren are better off in stepfamily situations than those where the parent did not remarry. However, they write stepparents do not feel the same “selfless commitment” common in genetic parents.
In response to their critics, Daly and Wilson cite that literally “hundreds of self-help manuals for stepfamily members” all focus on the difficult issue of how to cope with the characteristic conflicts of stepfamily life.
Research continues to verify findings of Daly and Wilson
Other researchers besides Daly and Wilson continue to verify their findings. For example:
- Schnitzer and Ewigman (2008) in the Journal of Nursing Scholarship found that children residing within households with adults unrelated to them had nearly six times the risk of dying of maltreatment-related unintentional injury. But risk was not higher for children in households with a single biologic parent and no other adults in residence.
- Stiffman, Schnitzer, et al. (2002) in the journal Pediatrics reported that children residing in households with adults unrelated to them were eight times more likely to die of maltreatment than children in households with two biological parents.
- Harris, Hilton, et al. (2006), in a study of 378 cases of filicide (killing one’s son or daughter), found that at least five times as many of the child victims lived with genetic fathers, while the raw frequencies of filicide were roughly equal between stepfathers and biological fathers.
- Tooley, Karakis, et al. (2005) reported that step-children under 5 years of age were at a significantly increased risk of unintentional fatal injury of any type, and of drowning in particular. They also reported that children from single-parent 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.
- A 2008 Scottish Government study found that living in a “reconstituted” family with step-children or stepparents increased the risk of developing behavioral problems.
The danger of ignoring the myth (that is backed by evidence)
The research by social scientists and epidemiologists undermines the Brady Bunch myth of a balanced family involving parents and children with no genetic relations—the guys in this family having no genetic relations to the girls. The more appropriate model to discuss the validty of research is the older and still maligned trope of an evil stepparent, notably the stepmother, as clearly acknowledged by Daly and Wilson in referencing Cinderella in their research title.
The wicked stepmother is a frequent character in folklore. This myth is older than feudalism, and found globally. The darker Brothers Grimm version of Cinderella (Aschenputtel) has her stepmother’s cruelty on full display, compared to simply wickedness in the Disney rendering. A recent cinematic evil stepparent was captured in the classic Cold War film thriller The Manchurian Candidate, which included an evil stepfather in partnership with his Soviet spy wife to manipulate her son to kill a presidential candidate and advance a dark Soviet conspiracy.
Joseph Campbell, author of Hero with a Thousand Faces, notes that myths incorporated the tools that people used, and those tools are associated with power systems that are involved in the culture of their time. In the case of the trope of the evil stepparent, the myth has not been supplanted. Evidence shows otherwise. It is still alive for good reasons.
Why this matters for policy makers
There continues to be great stepparents and foster parents, by the thousands. I know many great people in both camps. They deserve praise for doing a job that may have few rewards and tremendous stress. I am in awe of those who I personally know (colleagues in Alaska).
However, policy makers, educators, law-enforcement agencies and social service agencies need to be reminded of very real risks of some family situations. The New Zealand-based nonprofit called Child Matters notes that having a stepparent is a known risk that should be considered for the well being of all children.
Efforts by “soft” social science publications, like Pscyhology Today, to downplay the valid research into the hazards stepfamilies can pose to innocent children do not help the group that needs the help most of all.
Our larger understanding of stepparenting should not, as Daly and Wilson write, “suffer from the misconception that a ‘biological’ explanation for stepparental violence is a claim of its inevitability and imperviousness to social controls, which, if accepted, will excuse the violence.”
They rightly claim that these misunderstandings block progress in understanding and helping kids. Acknowledging the evolutionary process and its relevance to human affairs can only help. I believe Daly and Wilson are spot in their claim that the most harm is done by “those who adhere to the implausible notion that stepparenthood is psychologically equivalent to genetic parenthood and that ‘bonding’ experience is sufficient to evoke the full depth of parental feeling.”
(1) Daly M & Wilson M (2002). The Cinderella effect: parental discrimination against stepchildren. Samfundsøkonomen 2002 (4): 39-46.