Dangerous Steps

--Aug. 30: A five-year-old Santa Ana, Calif., girl is found unconscious with bruises on her body. After she dies, her 28-year-old stepfather is charged with child abuse resulting in death.

--Oct. 2: A 35-year-old man in Dayton is arrested for beating his stepson with a hammer, causing multiple skull fractures and a broken leg.

--Oct. 13: A 26-year-old man in Chicago is charged with beating his three-year-old stepson to death. The medical examiner's report details severe injury and abuse occurring over a period of time.

Tragic stories like these fill the nation's newspapers. But do they have any relevance to stepfamilies as a whole? Yes, say Martin Daly and Margo Wilson, two Canadian psychology professors at McMaster University in Ontario. In their slender new book, The Truth About Cinderella: A Darwinian View of Parental Love (Yale University Press), the duo argue that having a stepparent is the most powerful risk factor for severe child abuse. In fact, they say, an American child living with one genetic parent and one stepparent is 100 times as likely to suffer fatal abuse as a child living with two genetic parents. In Daly and Wilson's studies, a stepparent can also be an opposite-sex partner who lives with the parent, like a boyfriend.

Their reasoning, based on research in the U.S., Canada, Britain and Australia, won't sit well with many stepparents. "Because parental love carries with it an onerous commitment, it would be strange if merely pairing up with someone who already had a dependent child were sufficient to fully engage the evolved psychology of parental feeling," they write. "And it is not sufficient. Stepparents do not, on average, feel the same child-specific love and commitment as genetic parents, and therefore do not reap the same emotional rewards from unreciprocated 'parental' investment." Violence, they say, is just one, albeit dramatic, consequence.

In their view, it is no accident that fairy tales with wicked stepparents, like "Cinderella," can be found in every culture. The French even have a proverb for this: "Quand la femme se remarie ayant enfants, elle leur fait un ennemi pour parent" (The mother of babes who elects to re-wed/ Has taken their enemy into her bed).

Similarly, there are animals that turn on their predecessor's offspring, the authors say. "How do [male tigers] respond to the cubs sired by their predecessors? The grisly answer is that they systematically search them out and kill them." The Darwinian reason, say Daly and Wilson, is that all animals, including humans, prefer to promote their own "genetic posterity." Unrelated youngsters don't necessarily fit into that scheme.

Daly knows that their work, first published last year in England, is hard for some people, particularly nonacademics, to handle. "One thing that has fascinated and puzzled us is the fact that people don't seem to like this finding. I'm not sure what that's about," he says. "Stepfamilies are conflictual. Everyone who studies them knows that. But there's a widespread feeling that somehow to make too big a deal of it or to talk about that too much is exacerbating their problems instead of helping them." Still, he holds his ground. "Single parents might do well to be aware that there are a lot of risks in step relationships, and they should assess new partners in part with that in mind."

Daly and Wilson's findings win support from many experts. "I think it's pioneering work," says Stephen Emlen, a professor of behavioral ecology at Cornell. And the picture is not bleak, he says. "The evolutionary approach is basically saying we carry with us some genetically influenced tendencies to behave in certain ways in certain situations. It by no means says these cannot be overcome." Emlen compares this with discovering that you are carrying a gene that statistically increases your potential to develop a disorder. "Being armed with that knowledge can be very, very empowering. You're consciously going to do everything you can to minimize that risk."

Violence is not the only negative trait that runs in some stepfamilies, say experts. "We know that there's less of a sexual taboo in stepfamilies because you don't have the biological connection," says Dr. James H. Bray, author of Stepfamilies: Love, Marriage and Parenting in the First Decade. As a result, says Bray, "if a woman is about to remarry, she really ought to get to know her spouse and know some of her potential spouse's family history, because we know that sexual and physical abuse tends to run in families."

It's important to remember, however, that academic theories don't explain what goes on in individual homes. "We're looking to explain patterns of child maltreatment," says Richard Gelles, a professor of social welfare at the University of Pennsylvania. "But a broad social theory can't explain a single case." It just serves to alert families to the possible risks.