The ‘Cinderella Effect’: Why Stepdads Kill Their Partner’s KidsPsychological Phenomenon May Explain The High Numbers Of Similar Cases

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  • The ‘Cinderella Effect’: Why Stepdads Kill Their Partner’s Kids

The death of a child is always a tragedy, but it seems even more so when the individual behind the death is someone the child should be able to trust: their step-parent.

It’s something that happens far too often.

In fact, studies looking into the rate of deaths in children under five in Australia have uncovered that there is a disproportionately large number of step-dads killing their partner’s children. It’s something that researchers have come to call the Cinderella Effect.

What Is The Cinderella Effect?

The Cinderella Effect is the term used to explain the phenomenon of step-parents, not always men, being far more likely to kill their partner’s children than biological parents. The controversial theory was constructed by Canadian Martin Daly in the 1970s, and suggests that the reason behind the killings is that we are not biologically programmed to raise other people’s children. So when issues do arise, generally in homes where families struggle with alcohol, drugs and economic instability, the Cinderella Effect comes into play.

An Australian Study

Studies on the Cinderella Effect are being conducted all over the world, including in Australia. Melbourne’s Deakin University Professor Greg Tooley has been exploring the phenomenon with Australian numbers, culminating in a study of almost 900 child deaths.

Prof. Tooley told that the Cinderella Effect was “very well supported by the empirical evidence in multiple countries, especially the United States and Canada.”Stay At Home Mum

He noted that many people rejected the theory, something he put down to its confronting message and the fact that people “don’t like to think human behaviour is programmed and responsible to things like evolutionary pressures”. However, while it does put a pin in notions of free will, the statistics couldn’t be denied.

“If you look at the data, for children aged under two in the US who live with one non biological parent, and they are overwhelmingly male because most kids stick with their mums, they are more than 100 times more likely to die from physical abuse and 40 times more likely to be physically abused,” he told

Prof. Tooley said what it comes down to is human programming. When we become parents we are programmed to follow out the duties that job comes with, which includes ensuring no harm comes to our kids. However, step-parents don’t have the same programming, which means they don’t always act the same way.

“It’s not that step-parents are bad intrinsically,” he said. “It’s just these mechanisms don’t kick in the same way as biological parents.”

Cinderella Effect - Stay At Home Mum
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Not Just Violent Death

Unfortunately for step-children, the potential for harm doesn’t end at step-parent violence. Professor Tooley’s study found that kids in a family with one non-biological parent weren’t just 17 times more likely to die from intentional violence or accident. They’re also more likely to be at risk of everything from drowning to fatal car accidents.

“Statistically kids in those situations are less likely to be cared for,” said Prof. Tooley.


Cinderella Effect - Stay At Home
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Adoptive vs Step

Interestingly, adoptive parents did not come up as often as step-parents in terms of child deaths, despite them also having no genetic connection to their children.

According to Professor Tooley, this can be explained quite easily. While adoptive parents have made a “conscious decision to parent a child even though they aren’t their biological parent”, step-parents usually only become parents as an extension of their romantic relationship, so they’re not making a “conscious decision to become parents”.

At The End Of The Day

While the Cinderella Effect doesn’t do much to improve confidence in the caring abilities of step-parents, Professor Tooley said that the vast majority of step parents “still managed to be good to their step-children”. But that doesn’t mean that the Cinderella Effect wasn’t real.

Professor Martin Daly, who coined the phrase, said that there was no doubt the Cinderella Effect was fact, even though “There are some people who desperately want to say this ain’t so”.Cinderella Abuse - Stay At Home Mum

Prof Daly suggested that couples planning on living together with kids from previous relationships should get counselling when conflicts arise between step-parents and children. He also recommends caution, particularly among those who delude themselves into believing their partners will automatically love their kids.

“You’re exacerbating the resentment rather than alleviating it. People aren’t spontaneously inclined to love just any kid on the block.”

It might not be a pretty picture, but a bit more awareness about the Cinderella Effect could save lives, and stop so many Australian families from being unnecessarily plunged into grief.

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