Do older children influence their siblings’ willingness to take risks?

We pick up a lot from our big brothers and sisters – bad habits, good advice and maybe even the way we think about risk.

In a new study, researchers found that observing an older sibling’s risk-taking can change the behaviour and brain patterns of younger siblings. It all depends, however, on their relationship.

“Siblings influence one another on multiple levels, and this also includes the brain,” says Christy Rogers, Assistant Professor in Human Development and Family Sciences at Texas Tech University, who led the study.

Traditionally, sibling research has relied mainly on surveys, which offer rich insight over time but can have limitations, Rogers says. This study was unique in that it showed how siblings can influence each other’s behaviour in real time and offered insight into neurobiological outcomes.

“Researchers found that observing an older sibling’s risk-taking can change the behaviour and brain patterns of younger siblings.”

The study, published in the Journal of Research on Adolescence, involved 43 pairs of one older sibling aged 14-17 and one younger sibling aged 11-13. To test their risk-taking, the researchers had each older and younger sibling play a driving simulation game. Then, while undergoing an fMRI scan, the younger siblings were shown a recording of the older siblings’ games, after which they were asked to play the game again. Children emulated the risk-taking behaviour of their older sibling when playing the game a second time, becoming more likely to take risks if their sibling took a lot of risks or more cautious if their sibling played it safe.

Examining the brain scans of the younger siblings, Rogers and her colleagues found that children who reported looking up to their older siblings had more similar brain patterns to them, and specifically that their neuronal activity was more similar in the ventromedial prefrontal cortex. This area is associated with the evaluation of rewards and choice, suggesting that these siblings share similar values.

However, younger children don’t always follow the lead of their older siblings; indeed, in some cases they may even rebel against them. In a follow-up study, currently undergoing peer review, Rogers looked at the characteristics that influence how adolescents process the behaviour of their older sibling. She observed that the children who took part in the study seemed to exhibit different brain patterns depending on the level of influence of their older sibling as a model, such as whether they were of the same sex, whether they were close in age, and whether they were regarded as a role model rather than as someone to differentiate themselves from. All of the younger siblings observed their big brother or sister closely, but they processed their observations in different areas of the brain, depending on the sibling dynamics.

“This new research can help explain how adolescents learn to make decisions about risk-taking.”

Guiding children through adolescence

Adolescence is a time when children are more likely to engage in more risky behaviours such as sexual relationships, drug use and drinking. This new research can help explain how adolescents learn to make decisions about risk-taking, and can shed light on the unique influence of older siblings.

“You might say that older siblings have a foot in two worlds. They act like a peer in some ways, but sometimes like a parent, too,” Rogers says.

“Siblings can provide the advice needed to guide a young person through the awkward and oftentimes challenging experiences of adolescence.”