BEIJING-Swedish researchers investigating child homicide rates in stepfamilies have found that child victims were equally likely to be killed by their biological parent as their stepparent.

This finding, published in Current Zoology, is in opposition to the 'Cinderella-effect', a term used by psychologists to describe the high incidence of abuse of stepchildren by their stepparents.

Proposed reasons for this observation include the higher rates of criminal activity and psychiatric problems in stepfamilies, and conflict between couples in stepfamilies, as opposed to an evolutionary or biological reason related to genetic relatedness.

The researchers analyzed Swedish records for child homicides with parent or stepparent perpetrators from 1965-2009. They found that children in stepfamilies are more likely to be murdered than children living with both biological parents, but not necessarily by their stepparent.