If you saw our video about becoming your parents, you learned how you could pick up some of your parents' habits and traits— although ultimately your decisions are in your control.

And turns out, you could get some really unhealthy things from your parents, too. So you know, we're going to talk about disturbing behaviors like domestic violence and child abuse.

Just in case you'd like to avoid those things. [INTRO ♪]. Psychologists use the phrase intergenerational transmission of violence to refer to the fact that children who grow up with abuse are more at risk of being abusive as adults. In other words, "violence begets violence." Psychologists have also found ways that people avoid this cycle, so it's not a definite thing.

But we do know that growing up with violence creates risk. For example, a 2010 study published in the Journal of Interpersonal Violence followed a random sample of a thousand 7th and 8th graders until they were an average of 33 years old. Overall, adults who were abused as children, ranging from neglect to physical or sexual violence, were almost two and a half times more likely to mistreat kids.

But it also mattered when the subjects of the study actually experienced abuse in their lives. Adults who were abused as adolescents were almost five and a half times more likely to be abusive than a person who hadn't experienced any violence in their home. But the effect basically went away for people who were only abused as young children, when they were less than 12 years old.

So they seemed more likely to escape the cycle of violence. It's worth mentioning that the control group— those who hadn't experienced violence as kids— wasn't immune to developing violent behavior, either. They just didn't seem to carry that extra risk.

In fact, about 10% of the people in the control group turned out to be abusive in some way— compared to 18% of people who were abused as children, and 37% of people who were abused as adolescents. Now, the risk could also change if someone was a victim of abuse, or if they just witnessed it. An earlier study in 1984, published in the Journal of Marriage and Family, looked at factors that might predict violent behavior in more than 2000 adults.

And the researchers found that observing domestic violence between parents tended to more accurately predict violent behavior than being physically abused. So why do these patterns exist? Probably one of the most important ways is because we learn behaviors that are modeled by our parents or caregivers, including harmful ones.

This is called vicarious learning, and was famously studied by Albert Bandura using inflatable clown toys, called Bobo dolls. If kids watched adults hit and throw a Bobo doll, they were more likely to be violent to the toy too. So if kids see parents using violence to get what they want, whether it's spanking a child or hitting a partner, they might learn to deal with their conflicts with violence too.

But there's also a lot of variation among kids— some pick up modeled aggression more readily than others. And as children grow up, they'll have other models and can learn from them, too. Plus, people can make choices about how they behave, so they won't necessarily resort to violence, and can break away from unhealthy patterns.

But part of the reason these patterns exist might also be genetic. Researchers find that people's self-reports of aggressive behaviors can be partially explained by their genes. But genetics actually aren't that simple.

How much influence your genes have can depend on what your environment is like. When it comes to psychological disorders, this is called the diathesis-stress model. It's the idea that even though people might carry a genetic risk for some problem, it would take some kind of major life stress to trigger it.

Usually we think of stress coming from things like relationship drama or problems at work. But research has also found that significant stress can be caused by systemic conditions like poverty— for instance, if you feel unsafe, or if there's poor-quality housing and very few resources like stores or buses. These kinds of environmental stresses have been linked to mental health issues that have a genetic component, like clinical depression.

And there's some specific evidence for the diathesis-stress model when it comes to abusive behavior. For example, a 2002 study published in Science looked at data from just over 1000 people who carried a gene that codes for an enzyme called monoamine oxidase A, or MAO-A. When this gene is working, the enzyme helps break down different neurotransmitters like norepinephrine, serotonin, and dopamine.

These chemicals are involved in a lot of brain processes, potentially including how stressful experiences affect long-term behavior. A lower-activity version of the MAOA gene— meaning less enzyme gets made— has been linked in some studies with a higher risk of displaying violent or antisocial behaviors. But in this analysis, the researchers found that people with a lower-activity version of the MAOA gene had a higher risk specifically if they had been mistreated as children.

People with that version of the gene who weren't mistreated had a comparatively lower risk. So the gene seems to be influenced by stress in some way. It's not straightforward.

But even though genetics might play a role, it doesn't mean abusive behavior is inevitable. An important way to break the cycle of violence is through help from professionals. Several therapies that teach adults skills to help them interact with children have been shown to reduce the chance of abusive behaviors in people who are at risk of showing them.

One 2007 study published in the journal Child Abuse & Neglect looked at people who received a treatment program focusing on interpersonal and relationship skills. These people had lower rates of partner violence than an at-risk control group— measured at a check-in 16 years after the program ended. So, unfortunately, abuse is a distressing example of how we can learn harmful behavior from our parents.

But nothing is set in stone. Through more research, therapy, and more people being conscious of risks and seeking help, psychologists are working to improve lives. And, in the end, you get to choose who you are and what you do.

Thanks for watching this episode of SciShow Psych. If you're interested in learning more about complicated and potentially harmful relationships, you can check out our video about codependency. [OUTRO ♪].