Human Behaviour Intended to Harm Another Individual

Psychologists define aggression as “behaviour intended to harm another individual who doesn’t wish to be harmed”. Intention plays an important role when it comes to aggressive behavior, as a behaviour may be considered aggressive when that wasn’t it’s intent, however, intentional harm is, in any case, seen as more regrettable than unintentional harm, even when the harms are indistinguishable. Is this aspect of development genetically inherited or does it originate from the environment one grows up in? 

The nature versus nurture debate is one of the oldest debates within psychology. The nature versus nature theory was coined by English psychologist, Sir Francis Galton in 1869 who studied this subject notably in Hereditary Genius. The nature side of the debate argues that our traits are determined by our DNA and genotype that we were born with whereas the nurture side argues that we acquire our traits through learning and our environment. This essay will discuss the extent to which aggressive behaviour in children, prepubescent minors, is influenced by nature and nurture.

Twin and adoption studies are used to demonstrate a genetic inheritability. Rhee and Waldman’s meta-analysis included a 51 twin and adoption studies aggressive behaviour in children. Genetic factors explained 41% of the variance in antisocial behaviour while 59% was explained by environmental influences. The study suggests that aggressive behaviour shows high heritability. However, twin and adoption studies contain methodological flaws and are subject to the confounding influence of environmental factors. Therefore, Rhee and Waldan’s conclusions might not be supported by enough evidence.

Coccaro et al. ompared American veteran’s criminal behaviour, specifically aggressive behaviour, amongst 182 monozygotic (MZ) and 118 dizygotic (DZ) male-male twin pairs. The MZ twin pairs were found to have a 50% concordance for physical aggression whereas DZ twins were only 19%. As the MZ are genetically identical, the research supports the role of genetics in aggression. This researched emphasises the role of genetic factors in aggressive behaviour in children, but environmental factors remain important. This study assumes that the participants were brought up in equal environments.

Researchers have tempted to explore the particular genes potentially responsible for aggressive behaviour in children. Beitchman et al. (2006) examined the link between the serotonin transporter (5-HTT) gene and childhood aggression. This was done by testing the serotonin transporter promoter polymorphism (5-HTTLPR). Eighty-two clinically referred children aged five to fifteen years old displaying behaviour for at least two years were genotyped for 5-HTTLPR. It was concluded that aggression was linked to the low expression of the genetic variant of the 5-HTTLPR polymorphism. The main criticism of this study is that comparison subjects were adults reporting on their mental health during childhood. The comparison subjects were allegedly mentally healthy in order to compare the aggressive children’s genotype to theirs.

Caspi et al. (2002) explored the genetic relationship between people who had been maltreated during childhood and antisocial behaviour as adults. This was a longitudinal study of criminality in New Zealand of 1,037 people (52% male) from birth until 26 years old. Monoamine oxidase A, the enzyme encoded by the MAOA gene, was found to be the source of aggression in maltreated children. Indeed, 85% males with low MAOA activity in conjunction with maltreatment developed antisocial behaviour. Therefore, differences in the gene MAOA were associated with aggression and these results explain why only some victims of maltreatment in childhood grow up to display aggressive behaviour. This research is epidemiological evidence that genotypes can moderate a child’s sensitivity to its environment. Antisocial and aggressive behaviour are both influenced by nature and nurture.

Early research by Bandura suggests that aggressive behaviour can be learnt indirectly by observational learning. Social learning theory (SLT) states that young children learn aggressive acts by imitating a role model, usually a parent. Bandura proposed five cognitive meditational processes that control aggressive behaviour. These occur between stimuli and responses: the individual must be observant of their role model’s aggressive behaviour (attention) in order to retain this behaviour (retention) and have the physical ability to reproduce it (production). If the behaviour is rewarded reinforcement and if this reinforcement outweighs the negative impacts, the observer will be more likely to imitate the aggressive behaviour (motivation). Finally, the individual must be assertive that in a given situation, aggression is the appropriate behaviour to receive a positive outcome.

Bandura et al., (1961) demonstrated the theory of transmission of aggression with the Bobo doll experiment. The study included 72 preschool children aged between 3 to 6 years children with an equal number of both boys and girls. A third were exposed to violent behaviour towards a large inflatable doll (the Bobo doll), another third were exposed to non-aggressive behaviour towards the doll and the final third were not exposed to any model. The three groups were then split into six subgroups according to gender. 

Half of the subgroups observed a same-sex behaviour model and half would observe an opposite-sex behaviour model. In a second room, all children were exposed to aggression arousal by being told that that they could no longer play with the given toys. They were then taken to a third room in which they could play with aggressive and non-aggressive toys including the Bobo doll. Children who had watched aggressive conduct in the first room were bound to mirror this conduct. Boys were bound to emulate a model of similar sex and imitated twice as more physical violent acts than girls. Within same-sex aggressive groups, boys were bound to emulate physical violence while girls were more likely to mimic verbal aggression. 

This experiment translates Bandura’s theory that children learn aggressive behaviour by observing the behaviour of another person. While this study successfully supports Bandura’s theory, it has been criticised notably for the fact that the relationship between adult and child doesn’t translate the familiarity between a child and a parent or close role model. Cumberbatch argues that the novelty value of the doll encourages children to imitate the modelled behaviour. The research does not measure the long-term effects of the exposure if there are any and it is conceivable to argue that the study was unethical.

SLT can be applied in a different context in which role models aren’t a child’s parental figure but a form of media. Aggressive behaviour can be taught through imitation of different types of behavioural models and factors. Those factors exert their influence by encrypting social scripts, behaviours that are expected in a particular situation: children learn aggressive scripts. Huesmann et al. explored the relationship between children’s exposure to television (TV) violence and their aggressive behaviour in young adulthood. 

This longitudinal study involved 557 children subjected to TV‐violence viewing from the first grade. This exposure anticipated adult physical hostility 15 years later for both men (r = 0.17) and women (r = 0.15) and indirect aggression for women (r = 0.20). The study concluded that children exposed to TV-violence at an early age are likely to illustrate aggressive behaviour in adulthood. It supports the Nurture theory as it confirms that children learn, model and imitates aggressive behaviour.

Gentile and Gentile’s study (2008) explored the relationship between aggressive behaviour in children and video games. Four hundred and thirty 430 third- to fifth-grade children were followed across a school year. Those who played violent video games regularly were more likely to display traits of hostility and get into physical fights. Boys play video games more regularly than girls and report an inclination for more violent games. Despite these gender differences, Anderson and Bushman (2001) did not find that gender directed the negative impacts of violent video games, suggesting both genders may be influenced by violent media similarly.

Parenting methods have a great influence on a child’s development. Waller et al., investigated whether parenting is an environmental factor of aggression in children. The study included 227 monozygotic twins pairs aged from 6 to 11 years old. It was found that the twin who had been exposed to more severe parenting showed more signs of aggressive behaviour (r = 0.51) as opposed to a warmer parental approach (r = −0.10). This study is evidence that parental influence plays a major role in a child’s aggressive behaviour. More specifically, severe parenting methods will more likely encourage the child to display aggressive behaviour.

Harris's group socialization theory (1995, 1998) may have a large impact on children’s aggressive behaviours. Shi and Xie (2020) examined this behaviour in 245 seventh-graders. High‐status peers had a solid impact on individual members' physical and social aggression. A comparable design was found for physical aggression in boys' groups. These findings infer that high‐status members' aggression rather than the average of all members' may better represent the group norm.

This essay has discussed how aggression in children is influenced by nature, exploring the specific genes responsible for such behaviour, including 5-HTTLPR and MAOA. Genetics can moderate a child’s sensitivity to its environment, meaning aggressive behaviour is heavily influenced by nurture, especially by parents or role models according to Bandura’s SLT, the media according to Huesmann and our peers according to Harris’s group socialization theory. This aspect of children’s developmental psychology isn’t influenced by one of the two elements of the debate, but rather by both simultaneously. Scientists and psychologists continue to research this subject to understand the number of aspects that contribute to this behaviour.