Some time ago, news reported that Liu Moumo, a 15-year-old girl in Heilongjiang, killed her mother in December last year and hid her corpse in a cold storage room, and then faked the scene until her father found the body later. After calling the police, after investigation, the police identified the girl as suspected of committing the crime. After a sudden trial overnight, Liu Moumou explained the whole process of killing her mother.
Earlier on April 18, 2020, the Xuancheng police in Anhui issued a notice that the girl Yang Mouting, who had been lost and reported to the police, was killed by her 13-year-old cousin Yang Moumou.
In recent years, juvenile delinquency has become commonplace, so some people ask, are there really “natural born criminals” – some people are born easy to commit crimes?
As early as December 1870, in the prison of Pavia, Italy, an Italian criminologist named Lombroso opened the head of the corpse of the famous bandit leader Vileira and found There is an obvious depression in the occipital part of its skull, and its position is the same as that of lower mammals. It was concluded that this situation belongs to the true earthworm hypertrophy.
(Image credit: giphy)
Inspired by this, Lombroso followed up to investigate and measure the physiological characteristics of a large number of violent criminals, especially the anatomical structure of the brain and skull, combined with anthropometric measurements and facial analysis. , tattoo characteristics and other means, put forward the theory of born criminals, and published his famous work “criminal”.
Early studies on violence tended to be sociological, but since Lombroso, more and more experts and scholars have found that heredity, living environment and living habits are all related to violent aggression. certain connection.
In the 1990s, American scholar Coffey[1] found that some criminals had an extra Y chromosome (23XYY) when conducting chromosome tests on some male criminals. He believed that Men with an extra Y chromosome tend to be more aggressive and violent than men with a normal chromosome (23XY).
In a homicide that occurred in Chicago, USA in 1966, the murderer Speckbe killed 8 nurses in a row, and his later tests found that he was a typical XYY chromosome abnormality .
However, current research is looking for genes associated with violent aggression, especially some neurotransmitter-related genes, from the perspective of genetic polymorphism and epigenetics.
Example:
1. 5-hydroxytryptamine (5-HT), widely involved in the functional regulation of mood, pain, and sleep
The abnormality of this neurotransmitter can easily lead to abnormal impulsive aggression, suicidal antisocial behavior [2]. Its corresponding gene polymorphisms are also thought to be associated with violent aggression and impulsive traits.
On July 1, 2008, Yang Jia violently assaulted the police at the Zhabei branch in Shanghai, resulting in the death of many police officers. According to the criminal Yang Jia’s personality and behavior, some researchers infer that it basically corresponds to the performance of people with abnormal serotonin levels in the brain [10].
2. Catechol Oxidative Methyltransferase
Catechol oxidative methyltransferase is a metabolic enzyme whose primary role is to degrade catecholamine neurotransmitters, including dopamine. It is currently believed that some carriers of its related genes have susceptibility to violent aggressive behavior, and it has also been verified in patients with schizophrenia [3].
3. Dopamine transporters and receptors
Dopamine in the brain mainly regulates the brain’s desire, feeling, and transmits exciting and happy information.
When dopamine increases, normal fear is replaced by excitement, which can lead to more violent aggression. It has also been confirmed that specific polymorphisms of some related genes are associated with low attention, hyperactivity, and violent aggression in children [4].
4. Monoamine oxidase
Monoamine oxidase is an enzyme that catalyzes the oxidative deamination of monoamines. It is involved in the metabolism of catecholamines such as dopamine, norepinephrine, epinephrine, and neurotransmitters such as serotonin. Social personality disorder and violent aggression are associated [5].
5. GABA
γ-aminobutyric acid is an important inhibitory neurotransmitter in the brain, which has sedative and anti-anxiety effects. Genetic abnormalities of its receptors are considered to be related to personality abnormalities, Violent impulsive behavior is relevant [6,8].
Maybe one day, when we can fully determine the specific function and role of these defective genes, we can treat and improve these gene carriers by means such as surgical treatment of “cleft lip”.
Not necessarily!
Violent aggression is a complex behavior that is influenced by a combination of genetic and environmental factors.
Factors such as alcoholism, smoking, and childhood adversity can all play a significant role in violent aggressive behavior.
Generally speaking, criminal behavior is often the manifestation of the criminal’s personality and social defects, and its essence is the attitude of hostility, contempt or indifference to social norms and laws.
It is with these incorrect attitudes that they choose behaviors that society does not approve of to meet their needs. However, those who carry genes with a tendency to violent behavior and who have personality defects may not necessarily commit crimes.
Because whether it is the gene carrying of violent aggression or personality defect, when they are transformed into a criminal mental state, they must also depend on certain subjective and objective conditions, which are only necessary conditions for the production of criminal psychology rather than a sufficient condition [9].
Reviewer: Xu Hao| Neurosurgeon, Science University V
References
[1]Coffey MP.The genetic defense:excuse or explanation? [J]. William and Mary Law Review . 1993,35(1):353-399
[2]Frankle W Gordon et al. Brain serotonin transporter distribution in subjects with impulsive aggressivity: a positron emission study with [11C]McN 5652.[J]. The American journal of psychiatry, 2005, 162(5) : 915-23.
[3] Wang Yongbai, Wang Jiakai, Gang Qingwei, Liu Jingyi, Wang Jing. A meta-analysis of the association between the Val158Met polymorphism of COMT gene and violent behavior in patients with schizophrenia [J]. China Journal of Mental Health, 2014, 28(07): 492-498.
[4]Guoqin Hu et al. The interaction of NOS1AP , DISC1 , DAOA , and GSK3B confers susceptibility of early-onset schizophrenia in Chinese Han population[J]. Progress in Neuropsychopharmacology & Biological Psychiatry , 2018, 81 : 187-193.
[5] Major General Liu, Shi Yuxiu, Han Fang. MAOA gene polymorphism and aggressive behavior (review) [J]. Chinese Journal of Mental Hygiene, 2017,31(07):580- 584.
[6] Zhang Jingfeng. The influence of childhood adversity and genes on the aggressiveness of male prisoners [D]. Shenzhen University, 2019.
[7] Li Jiajue. Study on the correlation between methylation levels of NR3C1 and NR3C2 gene promoter regions and aggressive behavior [D]. Kunming Medical University, 2020.
[8] Li Hui, Li Lei, Xu Hongmei, Zhao Ziqin, Liu Wenbin, Zhou Huaigu. Research progress on the genetic correlation of human violent aggression [J]. Journal of Forensic Medicine, 2015, 31(05): 381-386.
[9] Mei Chuanqiang. Research on the mechanism of criminal psychology [D]. Southwest University of Political Science and Law, 2004.
[10] Qin Zhonghua. On the Practical Significance of the Research on Criminal Biological Causes [D]. Fudan University, 2008.
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