There are many factors in a teenagers life that can have an effect on their behaviour. Some features of teenagers behavioural development may be particularly responsive to environmental influences, while others may be more genetically determined and less flexible. On top of this, teenagers' social development and experience and family expectations, knowledge and labels for them can also impact their behaviours. All of these factors each play a role and all aspects must be considered when determining the cause of particularly disruptive of unwanted behaviours, such as shootings.

Some teenagers develop a pattern of problem behaviour which may involve excessive noncompliance, stealing, cruelty, inattentiveness, aggression or impulsivity involving conflict with others, while others may become withdrawn, depressed or anxious. These misbehaviours only become troublesome when they are persistent and have an effect on themselves or other people in their worlds. Too often, these patterns start in early childhood and continue to the teenage years. A range of risk factors for the development of problem behaviour have been identified and there is evidence that both biological and environmental factors play a role, and that these interact in complex ways.

Biologically, personality or temperament can affect teenagers' behaviour. There is greater recognition emerging in relation to the impact of temperament on the development of problem behaviour and the role of temperament in interventions designed to improve behaviour in young children, For example, difficult temperament in infancy is one of the major variables in the explanation of later aggressive behaviour and it has been found that children with a combination of high novelty-seeking, low harm avoidance and low reward dependence are most at risk for the development of disruptive behaviour disorders in the short to medium term. Temperament traits are considered to be stable, biologically based characteristics that are visible from birth. However, they are not absolute, and can be receptive to environmental experiences. Nevertheless, dramatic change in temperament style is rare, for example, a shy child is unlikely to become a highly extroverted adolescent, and rather, small change is more common. Consequently, since temperament has a strong genetic component it is somewhat uncontrollable and can have an effect on teenager’s behaviour

In contrast, environmental factors have been shown to play a powerful role in the development of teenagers behaviour. Patterson, Reid and Dishion (1992) recognised that inept or harsh parenting was involved in the development of behaviour problems, particularly if a child’s personal characteristics already placed the child at risk for such problems. Similarly, evidence supports Conger’s Family Stress model (Conger, Conger, Elder, Lorenz, Simons & Whitbeck , 1992), which posits a chain of influences beginning with economic pressures on families, which affect parental and marital wellbeing and hinder parents’ capacity to rear their children effectively, which then impact on children’s adjustment throughout childhood. Identified risk factors within families for problem behaviour in teenagers include, dysfunctional families, economic hardship, exposure to acts of violence, poor quality relationships and/or poor attachment between children and their carers, child abuse, coercive and inconsistent discipline, parental stress and depression and low sense of parenting efficacy. Therefore, while child characteristics such as temperament style may predispose teenagers to develop behavioural or socio-emotional problems, environmental factors (particularly the family context and broader societal conditions) play a considerable role as well.

In addition a teenager may not necessarily be ‘naughty’, rather they just lack the social experience and skills to resolve certain situations.This lack of social experience and skills leads to mistaken behaviour. The cause of any mistaken behaviour is insufficient understanding about how to act maturely in the complex situations of life. Children who lack social skills often lean towards anger as a response when they do not know how to respond. Another factor contributing to teenager’s mistaken behaviour is the experimentation of the teenager. In certain life situations they have not had much experience thus they will learn through engagement and experimentation just as they would with other learning experiences. With a human’s need to learn and belong, but limited by the ability to balance their own needs with the needs of others, mistaken behaviours will occur.

Teenagers can socially learn mistaken behaviours intentionally or unintentionally reinforced by significant adults and peers in the their lives. Parents who are less responsive and more negative in interactions have problems providing the language-rich environment optimal for developing children's interaction skills.Children can also be influenced socially by other children and role models into mistaken behaviour. This often occurs in teenagers with low self-esteem and low proactive social skills, leading to imitation of unwanted behaviours during their interactions with their peers. Thus, social inexperience and lack of skills can affect children’s behaviours.

Lastly, inappropriate demands, knowledge and labelling by significant role models can affect teenager’s behaviours. Inappropriate demands on teenagers creates tension them and their emotional needs. These inappropriate demands usually are underpinned by a behaviouristic approach to learning behaviours and educators attempting to ‘control’ their children to meet the needs of the educator through operant and vicarious conditioning. This in fact leads to unwanted behaviours by the teenagers due to misunderstandings of the their development, needs and wants. Generally speaking teenagers act to satisfy their needs, not the needs and goals of other.

Therefore, a single misbehaiour is not an isolated event. It is a combination of biological and environmental influences throughout life leading to a certain behaviour. In this recent case a violent, agressive masacre suicide.