Criminal behavior has always been a focus for psychologists due to the age old debate between nature and nurture. For decades, evidence has been mounting in proof that criminality is a heritable trait itself. Is it the responsibility of an individual’s genetic makeup that makes them a criminal or is it the environment in which they are raised that determines their outcome? Perhaps having a genetic predisposition for criminal behavior does not necessarily mean one will behave in a criminal manner, but does being exposed to the right environment, prove to manifest criminal behavior or anti social behavior that may have never exposed itself otherwise?
What factors make a criminal who and what they are? Are they a product of their upbringing, their family environment, proof of monkey see, monkey do? There can be explanations ranging from behavior genetics, child development, personality theory, learning theory, and social psychology to describe a complex interaction of genetic and physiological risk factors with different variables that predispose a portion of the population to antisocial and criminal behavior. These can all be seen in several different studies, including evidence from twin studies, adoption studies, and family/peer environment.
In order to understand how genes and the environment can influence criminal behavior, one must first know how criminal behavior itself is defined. Law in our society is defined by our legal and social institutions, not biology (Morley & Hall, 2003). Criminal law can be defined as actions that have the potential to harm interests of both federal or state government (Schmalleger, 1996). This gives the definition of criminal behavior to envelope a wide context of activities, and because of this broad view, researchers tend to focus on the wide context of anti-social behavior (Morley & Hall, 2003).
There are several different ways that a deceleration of nature vs. nurture can be looked at. One way researchers can determine the influence of genetics or environments is through twin studies. Twin studies can be used to see which influences criminal behavior more, whether it is nature, or if it is nurture. They can support the contention that criminal behavior may be a heritable trait (Tehrani et al. 1998). Twin studies are conducted by comparing identical, or Monozygotic twins, and their rate of criminal behavior, with the rates of criminal behavior in fraternal, or Dizygotic twins. If the outcome of these studies shows a higher concordance rate for the identical twins than there is for the fraternal twins, then it can be assumed that there is indeed a genetic influence (Tehrani & Mednick, 2000).
During a study in Denmark, in an unselected sample of 3,586 twins pairs, it was found that identical twins were concordant for criminal behavior where only 22% of the fraternal twins were concordant for criminal behavior (Tehrani et. al. 1998). Due to the increase of concordance for the identical twins, it does suggest that identical twins inherit some biological characteristics that could increase their joint risk for criminal involvement (Tehrani et al. 1998).
Adoption studies are also used, and these are conducted due to the fact that they should be able to separate nature and nurture. This helps to examine the relationship between not only adopted children and their adoptive parents, but also adoptive children and their biological parents. Several of these adoption studies have shown that the inherited biological factors appear to have an effect on whether criminal behavior is prevalent or not (Tehrani et al. 1998). Criminal involvement was also found to be increased in those adoptees whose biological mothers had been incarcerated (Crowe, 1978). Fifty-two specific adopted away children from Iowa were traced, being that they were the offspring of incarcerated women. Out of these 52, seven were convicted of a criminal offense, whereas only one was convicted in a matched control group (Tehrani et al. 1998). It was also found, that out of 246 adoptees in a different Iowa study conducted by Tehrani and colleagues, that anti-social adoptees were more likely than the control adoptees to have a biological parent who was also anti-social (Tehrani et al. 1998). This evidence supports the existence of a heritable component to anti-social or criminal behavior (Tehrani et al. 1998).
Family studies can be used as well to asses the relationship between nature and nurture on both anti-social and criminal behavior. Children are a product of both their genetics, and the environment in which they are raised, making it difficult to assign which behaviors are influenced by which factors (Brunner et al. 1993). This again raises the question of is it nature, or is it nurture?
In one noteworthy family study conducted by Brunner and colleagues to test the theory of nature vs. nurture, occurring utilizing a large Dutch family. In this study, a gene for Monoamine oxidase A, or MAOA was found to have a mutation (Brunner et al. 1993). This was cogent to the idea of nature, because MAOA is a brain neurochemical, and was associated with aggressive criminal behavior among a number of males in this family (Alper, 1995). The males of this family were also reported to have a deficiency in their MAOA, which can lead to a decreased concentration of 5-hydroxyzine-3-acetic acid in cerebral spinal fluid (Brunner et al. 1993). This proves an important factor, on account of the fact that evidence has shown low concentrations of 5-HIAA can be associated with impulsive aggression (Brunner et al. 1993).
Being that nature, when it comes to behavior, is something a person does not have control over, then one perspective that has to be taken into consideration, is the release of neurochemicals in the brain. Behavior patterns in specific parts of the brain are controlled by the release of a certain nuerochemicals, which then are responsible for these preeminent behavior patterns (Elliot, 2000). Monoamine oxidase (MAO) is a neurochemical that has been shown to be related to anti-social behavior. When the release of this chemical is low, it results in disinhibition, which can also lead to aggression, and impulsiveness (Elliot, 2000). MAO is associated with many neurochemicals that have already shown to have a link to criminal or anti-social behavior, and is related to other chemicals, such as nor epinephrine, epinephrine, and dopamine, all of which have been found to be affiliated to the personality factor of psychosis (Eysenck, 1996). Seretonin, a neurochemical that plays an important role in personality traits such as depression, anxiety, and bipolar disorder, is also involved with brain development. During this development, if there is a disturbance, it can lead to an increase of aggression and impulsiveness (Morley & Hall 2003).
There are other neurochemicals in the brain that may also play a part in a personality disorder or trait. Of these, a neurochemical that is not only associated with pleasure, but is also chiefly seen to have an impact on aggression, is dopamine. (Elliot, 2000). Predatory aggression, as well as emotionally driven aggression, is accomplished by dopamine release (Elliot, 2000). A relationship is to be seen between the genes in the dopaminergic pathway, impulsiveness, ADHD, and violent offenders (Morley & Hall, 2003). These neurochemicals, and what they involve, give just cause to believe that it is nature that plays a role in anti-social, or criminal behavior.
Personality traits of individuals themselves needs to be appraised in determining whether it is nature or nurture that causes criminal and/or aggressive behavior. Impulsiveness and aggression have been two of the most commonly cited behaviors, when dealing with criminal or anti social behavior. (Morley & Hall, 2003). Such personality traits and disorders are considered essential in the diagnosis of individuals with anti social and criminal behavior. Three of the most prominent personality disorders that are shown to have a relationship with later adulthood behaviors are Attention Deficit Hyper Activity Disorder, or ADHD, Conduct Disorder, or CD, and Oppositional Defiance Disorder or ODD (Holmes, et al. 2001).
Attention Hyper Activity Disorder, as well as ODD, have also been seen to be possible precursors to more serious anti-social conduct behavior. Children who have ADHD are unable to not only understand consequence, but are also unable to learn from past behavior, and are at risk for developing ODD, or CD (Holmes, et al. 2001). Some of these children’s futures are also made worse because they more often then not continue this personality disorders into adulthood (Holmes, et al. 2001). These aforementioned personality disorders are risk factors to the development of Anti Social Personality Disorder, or ASPD (Morley &Hall, 2003). It has also been shown, that between 70 and 90 percent of violent offenders as adults were highly aggressive as children as well (Holmes, et al. 2001). These listed personality traits have been shown to be heritable at times as well. (Holmes et al. 2001).
Several theories exist which contend nature vs. nurture- and whether the influences are genetic or environmental. A theory that suggests an interaction between genetics and environment is the General Arousal Theory of Criminality (Eysenck, 1996). This theory states that it is the inheritance of a nervous system which is relatively insensitive to low levels of stimulation, and is the common biological condition underlying all of these behavioral predispositions (Mealy, 1995). Individuals with such a characteristic will be not only sensation seeking, but impulsive and extraverted as well. This is due to being under conditions of relatively low stimulation they find themselves at a suboptimal level of arousal (Mealey, 1995). For them to be able to increase their arousal, these people will be more likely to participate in an activity that is seen as high risk level, such as committing a crime (Mealy, 1995). A meta-analysis was performed by researcher Ellis, in support of the theory of arousal. This analysis, which found that criminality would be associated with a variety of indicators of lower than normal arousal, including childhood hyperactivity, recreational drug use, risk-taking, failure to persist on tasks, and preference for wide-ranging sexual activity (Mealey, 1995).
A theory has been proposed which relates sociopaths with their anti social behavior. According to this theory, there are two types of sociopaths, primary, and secondary (Miles & Carey, 1997). The primary sociopath lacks in moral development, therefore does not feel socially responsible for his actions (Miley & Carey, 1997). This sociopath is a product of their own personality, and genotype (Miles & Carey, 1997). The secondary sociopath develops due to a response in their environment, usually because of disadvantages of social competition (Miles & Carey, 1997). If one lives in an urban residence, has a low socioeconomic status, and/or poor social skills, it can cause an individual to be unsuccessful in reaching their needs in a way that is socially desirable, and this can lead into anti social or criminal behavior. The first type of sociopath is dependent on their personality and genetic makeup (Miles & Carey, 1997).
It has argued that because children in the upper class are less likely to suffer environmental risks predisposing them to criminal behavior than children in lower class, it is likely to be the result of a particularly strong genetic predisposition (Mealey, 1995). Three separate studies have been conducted which support this evidence. In 1976, Wadsworth found that in boys that became delinquent, there were physiological indicators of hyper arousal among the upper, but not the lower class children (Mealey, 1995). In 1984, Raine found indicators of hypoarousal in his upper- class antisocial subjects, but in his lower-class subjects, he found the exact opposite (Mealey, 1995). In 1987, Satterfeld found that the children that were of his lower-class subjects, those in a biological high-risk group were seven times more likely to have been arrested than those in his control group. He also found in retrospect, among his middle- and upper-class subjects, the rate was between 25 and 28 times (Mealey, 1995). This outcome was a result of lower rates of criminal activity in the control groups of the middle- and upper-class subjects as compared to the lower-class controls. It showed that, almost all of those who had been arrested from the middle- and upper-class were biologically at high risk, but that the children in lower classes were not biologically at higher risk (Mealey, 1995). The outcomes of these findings suggest that the effect of the social environment might be considerably larger than what have been suggested by adoption studies, and also that there might be different etiological pathways to criminal behavior (Mealey, 1995).
One question to be asked is at what point could nurture affect a child’s development? A factor that has been shown to increase aggressive and disruptive behavior in children, is maternal depression.(Goodmin & Gotlib, 1999). Maternal depression itself can aggravate the symptoms of violence seen in children, as well as affecting the cognitive and emotional development of the offspring (Hart et al. 1999). Pre-natal depression can be used as a factor to predict the level off aggression in children as well. (Hart et al. 1999). Aggression has been found to be associated with both medical, and risk factors in pregnancy, and early postnatal life (Raine, 2002). The behavioral outcomes of these children, born from mothers suffering postnatal depression, could actually be due to prenatal influences, since depression during pregnancy also exposes the mother to postpartum depression (O’Hara, 1997). During critical periods of development for the fetus, (especially during the second trimester) it has been found that if there is a neural disruption, there is an association to an increased risk of the fetus being convicted of a violent crime later in life (Tehrani, 1998).
A mother who has been suffering from depression has been found to be less likely to respond to the infant when the infant is in distress (Hart, et al. 1999). This lack of cognitive responsiveness to the infant’s needs is characteristic of depressed mothers, but due to this fact, an infant that is not taken care of when needed, less likely to be able to self regulate any response to frustration; this can be a predictor to behavior disorders (Wakschlag and Hans, 1999). When one is not able to manage and regulate anger and frustrations as well as other people , it has then been associated with violent behavior and other disruptive disorders (Weinberg & Tronick, 1998). This clearly delineates between nature and nurture because a child can not be responsible if their parents are not caring for them appropriately.
Social learning theory can be used as a way to explain how nature can influence a child and their behavior. This theory is to be used to explain a child’s aggressive or anti social behavior, meaning that the child has observed those behaviors of aggression and anti socialness already, either in their parents, or in a sibling, making it a learned condition (Miles, & Carey, 1997). Due to the children’s observations of this behavior, they grow to believe that this aggressive behavior is normal, and can act that way themselves, since they do not see harm in acting in a similar fashion as their parents (Miles, & Carey, 1997). Due to this fact, then environmental factors are also looked at when comparing nature vs. nurture. These factors can include parents, siblings, and peers, when looking at the Social Learning Theory. The family environment is critical to a child’s upbringing, and if there is a problem within this structure the child is the one more likely to suffer the consequence.
A theorist who believes in the social learning theory, a theory that can be used when showing the difference between nature vs, nurture, believes that positive and negative reinforcers are what are responsible for the aggressive behavior, as opposed to the belief that it is an internal, inborn behavior (Kalman & Waughfield, 1993). Frued claimed that aggression is an inborn drive, or an impulse, aiming towards destruction (Kalman, &Waughfield, 1993). Psychologist Horney rejected Freud’s theory that aggression is inborn, and claimed that both aggression and hostility, are responses to anxiety (Kalman & Waughfield, 1993). Another psychologist, Lorenz, claimed genetics and the environment are correlated, and said that aggressive behavior is innate, and that it demands criminal behavior to be carried out (Kalman, & Waughfield, 1993).
In showing that nurture plays a role in criminal behavior, a child that has a positive and caring parent-child relationship, with a stimulating home environment, and consistent disciplinary techniques, shows a relationship between the family environment, and the child’s behavior (Schmitz, 2003). If a family has a weak familial bonding, and poor communication within that family, children of this environment are more likely to develop either criminal or aggressive behavior (Garfenski & Okma, 1996). If a child is neglected or abused, they are also at a 50 percent greater chance of engaging in criminal acts than those children who were not (Holmes, et al. 2001).
The development of anti-social behavior, or delinquent behavior, can also be seen through these children’s adolescent peer groups. Involvement in these particular peer groups correlates to the conducting of problem behavior with these children (Garfenski ad Okam, 1996). The children of these groups were likely to have had aggressive behavior as younger children, having had shown aggressive tendencies towards their peers, therefore being deemed as outcasts (Holmes, et al. 2001). Children involved in these outcasted peer groups are in an environment of influence amongst one another, and this could push them more towards their criminal or violent behavior (Holmes, et al. 2001).
There cannot be enough possible evidence to conclude the point that genetics play the most important role in the outcome or behavior of an individual. The opposing viewpoint of environmental factors is not without its doubts either as to being the prominent factor associated with antisocial or criminal behavior of an individual. With the research and studies having numerous flaws and the inability to adequately separate nature and nurture, there is still a great debate between genetic and environmental factors. Therefore it seems obvious to reach the conclusion that an individual’s antisocial or criminal behavior can be the result of both their genetic background and the environment in which they were raised.
I also believe there is a great need to try and identify those individuals, especially children, who may become susceptible to certain disorders or personality traits that can lead into antisocial, delinquent, or criminal behavior. Society should not try to imitate the era of controlled breeding, but rather focus on the treatment and rehabilitation of those individuals in need. Certain educational, environment enrichment programs have been shown to have a lasting effect on children if given by a certain age. If more of these programs could be developed, society could help prevent the future antisocial or criminal behavior of children.
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