Children and adolescents may engage in occasional physical confrontations, but most do not develop a sustained pattern of violent behavior or engage in violent crime. Children and adolescents who become violent before puberty may be at higher risk of committing crimes.
Violent behavior is increasingly common among children and adolescents. Up to one third of children may be involved in bullying as bullies, victims, or both. Social stresses (eg, low family income, low parental education levels) are risk factors for bullying. In 2017, 24.2% of male high school students in the US reported carrying a weapon at least once during the month before they were surveyed as part of a study on youth risks (1 General reference Children and adolescents may engage in occasional physical confrontations, but most do not develop a sustained pattern of violent behavior or engage in violent crime. Children and adolescents... read more ).
Despite ongoing interest in the possibility of a relationship between violent behavior and genetic defects or chromosomal anomalies, there is minimal evidence for such a relationship. However, several risk factors have been associated with violent behavior, including
Intense corporal punishment
Alcohol and drug abuse
Gang involvement
Developmental issues
Poverty
Access to firearms
There seems to be a relationship between violence and access to firearms, exposure to violence through media, and exposure to child abuse Overview of Child Maltreatment Child maltreatment includes all types of abuse and neglect of a child under the age of 18 by a parent, caregiver, or another person in a custodial role (eg, clergy, coach, teacher) that results... read more 
and domestic violence. Children who are bullied may reach a breaking point, at which time they strike back with potentially dangerous or catastrophic results.
(See also Overview of Behavioral Problems in Children Overview of Behavioral Problems in Children Many behaviors exhibited by children or adolescents concern parents or other adults. Behaviors or behavioral patterns become clinically significant if they are frequent or persistent and maladaptive... read more and Behavior Problems in Adolescents Behavior Problems in Adolescents Adolescence is a time for developing independence. Typically, adolescents exercise their independence by questioning or challenging their parents' (or guardians') rules, which at times leads... read more .)
General reference
1. Kann L, McManus T, Harris WA, et al: Youth risk behavior surveillance—United States, 2017. MMWR Surveill Summ 67(8):1–114, 2018. doi: 10.15585/mmwr.ss6708a1
Bullying
Bullying is intentional infliction of psychologic or physical damage on less powerful children. Bullying can take several forms, including
Persistent teasing
Threats
Intimidation
Harassment
Violent assaults
Cyber-bullying (use of e-mail, texting, social media, and other digital communication tools to convey threats and/or spread hurtful information)
Bullies act to inflate their sense of self-worth. Bullies often report that bullying creates feelings of power and control. Both bullies and their victims are at risk of poor outcomes. Victims often tell no one about being bullied because of feelings of helplessness and shame and fear of retaliation. Victims are at risk of physical injury, poor self-esteem, anxiety, depression, and school absence. Many victims of bullying become bullies themselves. Bullies are more likely to be incarcerated in later life; they are less likely to remain in school, be employed, or have stable relationships as adults.
Gang involvement
Participation in gangs has been linked with violent behavior. Youth gangs are self-formed associations of ≥ 3 members, typically ages 13 to 24. Gangs usually adopt a name and identifying symbols, such as a particular style of clothing, the use of certain hand signs, tattoos, or graffiti. Some gangs require prospective members to perform random acts of violence before membership is granted. Increasing youth gang violence has been blamed at least in part on gang involvement in drug distribution and drug use, particularly methamphetamines and heroin. Use of firearms is a frequent feature of gang violence.
Prevention
Violence prevention should begin in early childhood. Strategies include
Violence-free discipline in young children
Limiting access to weapons and exposure to violence through media and video games
Creating and maintaining a safe school environment for school-age children
Encouraging victims to discuss problems with parents, school authorities, and their doctor
Teaching older children and adolescents strategies for avoiding high-risk situations (eg, places or settings where others have weapons or are using alcohol or drugs) and for reacting to or defusing tense situations
