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Does Being Cruel to Animals as a Kid Predict Later Criminal Behavior?

The popular press often reminds us of the graduation hypothesis, but there's more to it than that.
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(Photo: a katz/Shutterstock)

(Photo: a katz/Shutterstock)

New research by Kelly Knight, Colter Ellis, and Sara Simmons from Sam Houston State University investigates how many children are cruel to animals and whether it persists through generations. The study is especially valuable because it uses a sample that is representative of the United States population and tracks families over the years.

There are two main theories about childhood cruelty to animals. One theory is that if children are cruel to animals they will grow up to be violent adults. This is called the "graduation hypothesis." It rests on the idea that there is something wrong with the individual and that they "graduate" from animal abuse to interpersonal violence. This seems to be the theory we hear about most in the popular press. Although there is some evidence to support it, it may not be the whole story.

An alternate theory is that if a child is cruel to animals, it is a sign they have been subject to maltreatment of some kind and/or live in an environment of domestic violence. In other words, it could be a sign that something is wrong in the child’s life to cause them to behave this way.

It is a difficult topic to research. One of the problems is that many studies focus on a criminal or at-risk population. For example, if you study people who have been in trouble with the law and you find that many of them were previously cruel to animals, it is valuable information. However, there might be other people who were also cruel but did not grow up to be criminals, and who would not feature in your sample. Retrospective studies could also miss other important factors, such as the context provided by the family in which the person grew up.

About three percent of the parents said they had abused animals as a child. This number is higher than found in other surveys. The average age at which they said they started was 12.

Knight’s study uses data from the National Youth Survey Family Study, which ran from 1977 until 2004. There were 12 waves of data collection over three generations. By the end, the first generation to take part were grandparents. Since they had not been asked about animal abuse they were not included in Knight’s study.

There were 1,614 participants (1,067 children and 547 parents). The children were the third generation in the overall study, and were interviewed in 2003-04. Their parents had been interviewed many times over the years. In 2003, they were asked if they had been cruel to animals when they were children. The study also used data from an earlier interview in the late 1980s, when the parents (then aged 24-30) were asked about interpersonal violence.

About three percent of the parents said they had abused animals as a child. This number is higher than found in other surveys. The average age at which they said they started was 12. About three percent of the children reported animal cruelty, and 11 was the average age at which they said it began.

The results showed that people who reported being cruel to animals as children were more likely to be perpetrators of domestic violence as adults. This supports the graduation hypothesis. However, and perhaps surprisingly, they were also more likely to be victims of violence than those who had not been cruel to animals.

At the same time, the results showed that if the parents were perpetrators of violence then, 14 years later, their children were more likely to say they had been cruel to animals. This supports the idea that the family context plays a role in children’s violence to animals.

There was no link between the parents’ animal abuse and children’s animal abuse. In other words, cruelty to animals did not continue through generations of the same family.

Other variables such as gender, ethnicity, marijuana use, and depression also came into play, showing that the picture is complex.

"The implications of these findings are that early animal abuse is not only a risk factor for later involvement in IPV [Interpersonal Violence] violent perpetration but also violent victimization," the researchers write.

There are some limitations to the study, including the fact that only one question was used to assess animal abuse, and it relied on the person to define their own actions. But the size of the sample, the fact it is representative of the U.S. population, and the way it tracks families across the generations are extremely useful. The results improve our understanding of the links between interpersonal violence and cruelty to animals, and will help design better programs for children and adults who are victims of violence.

"The practical implications of this research for victim services, specifically, involve improving knowledge of the various pathways to and consequences of IPV, which can then be used to inform policy and program recommendations," the researchers write. "In addition, there is evidence suggesting that thorough measures of animal abuse are warranted in future studies of problem behavior."

It seems the links between animal abuse and interpersonal violence are more complicated than previously thought. Developing a better understanding will benefit both children and animals.