My brother, the daredevil

Research shows: We learn a lot from our older siblings - both good and bad habits and possibly also the way we assess risks. As researchers have discovered in a new US study, the behaviour and brain patterns of children can change when they observe the risk-taking behaviour of their older siblings. However, the influence depends on the relationship between the siblings.

Siblings can provide the advice needed to guide a young person through adolescence.

Researcher Christy Rogers

«Siblings influence each other on different levels, including the brain,» says study leader Christy Rogers, Assistant Professor of Development and Family Studies at Texas Tech University in the USA. According to Rogers, sibling research has so far relied mainly on surveys. Although these provide valuable insights, they may be limited. In contrast, the US researcher and her team have now been able to show for the first time in real time how siblings influence each other's behaviour. The team has also gained new insights into neurobiological effects.

The study, published in the Journal of Research on Adolescence, involved 43 pairs of siblings, with the older child aged between 14 and 17 and the younger between 11 and 13. To test their risk behaviour, the researchers had the siblings play a driving simulation game separately. The younger children then watched a recording of their older sibling playing while a functional magnetic resonance imaging scan was performed. The younger children were then asked to play again. The second time, the children imitated the risk-taking behaviour of their older siblings. In other words, they took more risks if their sibling had taken high risks, or played more cautiously if their sibling had favoured safety.

Similar values lead to similar behaviour

When examining the brain scans of the younger siblings, Rogers and her colleagues found that children who said they admired their older siblings had more similar brain patterns. In particular, the neuronal activity in the ventromedial prefrontal cortex was more similar. This area of the brain is associated with the evaluation of rewards and decisions. This suggests that the siblings in question have similar values.

Children played more cautiously when their siblings had focussed on safety.

However, children do not always follow the example of their older siblings. In fact, in some cases they may rebel against them. In a follow-up study, which is currently under review, Rogers investigated characteristics that influence how young people process the behaviour of their older siblings. She made an interesting observation: the extent to which the brain patterns of the children studied differed from those of their older sibling seemed to depend on how strongly the latter's role model function affected the child in question. For example, the same gender, a small age difference and whether the child regarded their sibling as a role model rather than as someone from whom they wanted to set themselves apart had an influence in this context. All children observed their older brothers and sisters very closely, but they processed their observations in different areas of the brain depending on the sibling dynamics.

Adolescence is a phase in which children are increasingly prone to riskier behaviour, for example by entering into sexual relationships, abusing drugs or drinking alcohol. The present study can provide an explanation of how adolescents learn to decide how to deal with risks. It can also highlight the particular influence of older siblings.

We learn a lot from older siblings. Possibly also the way we assess risks.

«You could say that older siblings each have a foot in two worlds. On the one hand, they sometimes act like peers, but on the other hand, they also act like parents,» says Rogers. "Siblings can provide the advice needed to guide a young person through the awkward and often challenging experiences of adolescence.