Does your baby sweat when scared? Don't worry 12-month-old babies who sweat more in scary situations are less aggressive at three years old On the other hand, those who sweat less and have a weaker fear response are more likely to be aggressive Is because they are less afraid of the consequences Could allow for the identification of high-risk children before their antisocial behaviour becomes a problem Parents who are concerned about their babies breaking out in a sweat have been told not to worry - it means they will be calmer toddlers. Scientists have discovered that 12-month-olds who sweat more when faced with scary situations will show less aggression than other children by the time they are three. Sweat monitors were attached to babies' feet to measure their reaction to loud noise and to a fear-inducing mechanical robot. 12-month-olds who sweat more when faced with scary situations show less aggression than other children by the time they are three The researchers compared the results with the children's behaviour, as rated by their mothers, when they reached the age of three. It revealed that babies with a strong physical reaction to fear and anger were less "physically and verbally aggressive" as toddlers. Professor Stefanie van Goozen, from Cardiff University's school of psychology, said babies with less nervous sweat were "more likely to engage in antisocial behaviour" as toddlers. She said: "Aggressive children may have lower levels of physiological arousal because they don't experience the same level of emotional arousal in response to fearful situations as their less aggressive peers. Because they have a weaker fear response, they are more likely to engage in antisocial behaviour. She explained: 'In order to behave aggressively you need to be relatively fearless - you dare to be aggressive and you are not held back by concerns that the other person could be aggressive to you. Most people are not aggressive because they are afraid of the consequences of their aggression. The anticipation of some form of punishment stops us from being too aggressive. She added: "These findings show that it is possible to identify at-risk children long before problematic behaviour is readily observable. Babies with a strong physical reaction to fear were less 'physically and verbally aggressive' as toddlers Identifying precursors of disorder in the context of typical development can inform the implementation of effective prevention programmes and ultimately reduce the psychological and economic costs of antisocial behaviour to society. Sweat levels are monitored by skin conductance activity (SCA) - how the body physically reacts when aroused by fear or anger. But Professor van Goozen said science has yet to discover why some babies have a stronger physical reaction to fear than others do. One theory is that it may be genetic - and that aggression in toddlers might be passed through the family. Professor Adrian Raine, Chair of the Department of Criminology at the University of Pennsylvania, said: "Stefanie van Goozen's latest novel findings are powerful in showing that objective physiological measures predict later aggression over and above other measures. If these new results can be replicated and extended to other ages, they have potentially important implications for the future prediction of aggressive and violent behaviour. They highlight the promise of biological measures too in better understanding the causes of fearless aggressive behaviour.