A team from the Institute of Child Health has found that brain damage inflicted on a specific area of the brain can lead to serious anti-social behaviour in puberty and adulthood.
The discovery raises the possibility that brain scans could be used in future to determine which people are most likely to suffer from long-term behavioural problems following an accident.
In both cases the ventral region of the frontal lobe of the brain was damaged - this is the area above the eye sockets.
By the early teens both boys were unable to control frustration or anger, could not monitor or control violent behaviour, had no insight into the consequences of their actions, and showed no concern for others.
One was almost expelled from school as a threat to his peers, while the other has a criminal record, and a drink and drugs problem.
Impulse control
The ventral part of the frontal lobes is thought to dampen down the desire to act on impulse - allowing people to learn how to behave appropriately.
This role clearly develops throughout childhood, however the two boys showed no significant concerns about behaviour until puberty.
Lead researcher Professor Faraneh Vargha-Khadem said: "We may be able to identify such cases in future, by brain scans following the accident.
"Not only might we be warned of such future problems but we may be able to correct them."
Professor Vargha-Khadem said the key to successful treatment would be to act as quickly as possible while the developing brain was most capable of adapting to change.
"If some key function is damaged in childhood, it is well established that other parts of a child's brain can develop so as to pick up such functions.
"Rigorous training in behaviour, social skills and rules of conduct would encourage other parts of the brain to acquire this crucial role."