How Older Siblings Lead Younger Siblings Into Trouble

A large informative sibling study has shown that older siblings who engage in violent criminal behavior influence younger siblings to do the same – especially if the siblings are close in age. As this work builds on prior work I’ve conducted with my collaborators, I wanted to expand on the findings and the implications for parenting.

Our research group has observed a similar sibling effect on delinquency in adolescence as well as early (illicit) use of tobacco and alcohol. The finding has been replicated by a number of other research groups. Of note is that in some of our studies, we could control for genetic similarity (by studying siblings who varied in their genetic relatedness, like identical twins versus fraternal twins, and full siblings versus half-siblings). While genetic makeup does convey some risk, we’ve found strong evidence that much of this influence is environmental in nature.

It’s especially important to recognize that there is good evidence that the siblings get into trouble together and function as “partners in crime.” We’ve conducted electronic diary studies in which siblings confirmed in real time assessments (known as ecological momentary assessment) that they were together, and doing things they shouldn’t be doing (often with mutual friends).

There is where age becomes a relevant factor. Sibling effects are driven by relationship dynamics – it’s the siblings who are close in age and who like to hang out with each other. Keep in mind that we’ve controlled for genetics in our studies, so this is an environmental affiliation. Siblings that don’t like spending time together typically don’t influence each other much. There is in fact a particular sibling relationship style that underlies the “partners in crime” phenomenon – it’s when the siblings have high levels of both positivity and negativity. They like being with each other – and also spend a lot of their time fighting.

So what should parents do? If you have an older sibling who is getting in trouble, be mindful that if they have a younger sibling (especially one close in age that they hang out with a lot) is at high risk for getting into trouble. It’s time to intervene with the older sibling – not just to help him or her, but also to prevent problems in the younger sibling.

Brothers Playing Video Games Together via


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