Is Problematic Behavior in Children Inherited or Environmentally Influenced Through Childhood Abuse and Domestic Violence?

Title: Is problematic behaviour in children inherited or environmentally influenced through childhood abuse and domestic violence?

Twins play an important role in studying the origins of certain traits or characteristics of individuals. Experiments or research carried out using twins are called twin studies, and can give insight on whether a particular trait is inherited (genetically influenced) or is environmentally influenced (Spinath, 2005; Weiner & Craighead, 2009). Twin studies are capable of providing such insight because identical or monozygotic (MZ) twins share 100% of their genes, whereas fraternal or dizygotic (DZ) twins share only 50% of their genes; and when a study shows that MZ twins have a greater similarity in the trait investigated with each other than DZ twins, the trait is considered to be inherited and not environmentally influenced (Spinath, 2005). In addition, environmentally influenced traits are categorized into two types: non-shared and shared environment. Non-shared environments are twins who grew up in the same environment but have acquired different traits (Towers & Neiderhiser, 2005). Shared environments however, are the complete opposite; it is when twins who grew up in the same environment have very similar traits (Dick, 2005). This piece focuses on the origins of problematic behaviour in adolescence, more specifically, whether their behaviour are inherited or influenced by their surroundings. Five article summaries based on twin studies are incorporated in this piece. Articles 1 and 2 studies the effects of domestic violence on antisocial behaviour, while articles 3 and 4 focus on the effects of child abuse and genetic and environmental influences on the development of drug and alcohol addiction respectively. Lastly, article 5 focuses on the development of violent behaviour in adulthood due to abuse during childhood. Each article is given a rating out of 10 based on 'relevance and usefulness', with 10 being the best.

Problematic behaviour in children such as substance abuse, disobedience or violent behaviour seems to be more genetically influenced rather than environmentally influenced. It is also dependent on the type of childhood the child had. Jaffee et al. (2002), Hungerford et al. (2012) and Forsman & Langstrom, found that children who developed problematic behaviour such as problems in cognitive functioning as well as violent behaviour due to exposure to domestic violence were genetically influenced. Nelson et al. (2006) and Knopik et al. (2009) however found that only problematic behaviours which involve substance use (alcohol and drugs) were more environmentally influenced. Knopik et al. (2009) in particular managed to show this clearly as they found that alcohol or smoking addiction cannot be inherited but problematic behaviour such as inattentiveness, impulsiveness, and conduct problems can. Therefore, problematic behaviour which focuses on violence and disobedience are inherited, whereas other problems such as substance addiction is environmentally influenced.

Article 1

Influence of adult domestic violence on children's internalizing and externalizing problems: an environmentally informative twin study

A majority of people believe that the manifestation of problematic behaviour in children caused by domestic violence is considered environmentally influenced as children would tend to mimic their parents' violent behaviour or become more emotionally unstable. However, studies have showed that adults who suffer from antisocial personality disorder, depression and addiction to alcohol or drugs are more likely to experience domestic violence. Therefore, domestic violence could just be a symptom of one of these psychiatric disorders, and problematic behaviour could have been passed down from the parents to children. In an experiment conducted by Jaffee et al. (2002), 1116 twins and their mothers were interviewed in the United Kingdom. The twin sample roughly contained an equal number of MZ and DZ twins. Research workers visited the homes of these twins and interviewed their mother (for history of domestic violence) and the twins (to examine any signs of externalizing or internalizing behaviour). Teachers of the twins were sent questionnaires to report the twins' behaviour in school. Results of this experiment showed that domestic violence had a greater impact on internalizing behaviour (5%) than externalizing behaviour (2%). However, MZ correlations for externalizing and internalizing behaviour were twice that of DZ twins, which indicates that genetic factors play a significant role in problematic behaviour. In conclusion, the main cause of problematic behaviour in children who experience domestic violence is heritability of psychiatric disorders, and domestic violence has higher contribution to externalizing behaviour than the environment. Further research should be carried out to determine if domestic violence is a factor which triggers problematic behaviour, or merely sustains it.

Rating: 8/10. The article contains relevant information and explores various third variables. The results and methods are also clearly presented.

Article 2

Exposure to intimate partner violence and children's psychological adjustment, cognitive functioning, and social competence: A review.

Aside from developing problematic behaviour in children, domestic violence could also impair the child's learning ability. In a review by Hungerford et al. (2012), the correlation between domestic violence and child's IQ was investigated. The participants in this reviewed study were 1116 British families with MZ and DZ twins. The results of the study showed the possibility of lower IQ in children being a genetically influenced trait. This result was evident when the correlation between lower IQ in children and domestic violence was higher in MZ than DZ twins. However, this is only true if the parents of these children had low IQs as well, because partners with lower IQs tend to be more involved in domestic violence. This study also discovers that exposure to domestic violence triggers aggressive behaviour in children more than problems in cognitive functioning such as lower IQs. In conclusion, a defect in cognitive functioning is correlated with domestic violence can be genetically influenced, but only if the parents have experience the same problem. Further research should be conducted, and include external factors which may have an effect on their cognitive functioning such as stress levels, social status and child abuse.

Rating: 4/10. The study in the literature review cannot provide information on whether domestic violence causes children to have lower IQ scores,