When researchers reported that stepfathers were more likely to kill children than biological fathers, the idea was quickly accepted and given a name; the Cinderella effect. It fitted too neatly into many pre-existing beliefs to be questioned much. However, when a new team of scientists took a deeper look at the data, they found the effect is not what it seems.
In the original Cinderella tale, the heroine's life is made a misery by a wicked stepmother, but in the 1970s it was stepfathers’ alleged great propensity to commit child abuse or even kill children that was given the name. Dr Gavin Nobes of the University of East Anglia has found that this inaccuracy isn't the only problem with the theory.
In the Journal of Experimental Psychology: General Nobes points out that previous studies on the effect used incomplete data, focusing only on children aged 0-5. Some casual partners of a mother with no connection to the child were also misclassified as stepfathers. When Nobes extended the sample to include all victims aged under 18, and was more rigorous about classifying relationships, he found much smaller differences between biological fathers and stepfathers.
If Nobes had stopped there, he might have concluded the Cinderella effect was real but greatly exaggerated. Instead, he looked to see if there were any other relevant factors that hadn’t been taken into account. He found the true danger element is not biological relationship, but age.
"In general, the data indicates younger fathers are more likely to abuse or kill their children than older fathers, regardless of whether they are stepfathers," Nobes said in a statement. “Also, the population surveys show stepfathers are, on average, much younger than genetic fathers. This means that the Cinderella effect can be at least partly explained by stepfathers' relative youth, rather than not being genetically related to their victims.”
Exactly why younger fathers are more likely to commit violence will require more research. Nobes notes they may be, on average, “less equipped to cope with the stresses of parenthood”. The influence of younger fathers usually being more financially stressed also needs to be explored.
The overwhelming majority of young fathers and stepfathers don't abuse, let alone kill, their children, but Nobes advocates prioritizing ways to offer young parents more support.
Although some scientists challenged the evidence for it, the Cinderella effect achieved widespread popular acceptance partly because it fit so well into our cultural heritage, including, most obviously, fairy stories. It also suited many ideological agendas. Evolutionary psychologists used it as evidence that people prioritize their genetic inheritance. Cultural conservatives seized on it to justify their views that divorce and remarriage are at the root of modern ills. Nobes' work is likely to be challenged in turn.