Due to the nature of juvenile delinquency, the problem of personality is placed first in the study of this phenomenon. A juvenile delinquent does not become that way suddenly, the moment a crime is committed. As a rule, the antisocial properties of his personality are formed gradually and long before the commission of a crime, which gives rise to a new qualitative socio-legal assessment of his personality as a juvenile delinquent. In other words, in the commission of any crime, first there is motivation, and then the crime is planned and executed. Therefore, since the main systemic elements of the crime are the properties of the individual and the external environment, that is, the social conditions of life. The causes of crime are analyzed by representatives of many sciences: lawyers, sociologists, psychologists, economists and even biologists. However, they do not provide a comprehensive explanation for all crimes. Let us then consider the discussion of biological and psychological theories on juvenile delinquents. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Biological Theory. Early attempts to explain crimes were mostly biological in nature: scientists looked for naturally conditioned reasons for the propensity of some people to commit crimes. Italian criminologist Cesare Lombroso concluded in 1870 that some people are born with criminal inclinations. In his opinion, criminal types can be defined by the shape of the skull. Lombroso did not deny the influence of society on the development of criminal behavior but believed that most criminals were biologically degenerate. Subsequently, ideas about biological predisposition to crime were sharply criticized. In the second half of the 20th century. Attempts have been made to link criminal inclinations with a certain set of chromosomes in the genetic code. It has been suggested that among criminals who commit serious crimes, the proportion of people with an additional Y chromosome is disproportionately high. In a series of studies conducted in maximum security prisons, a result was obtained showing that this deviation was one in hundreds of prisoners, compared to one in a thousand people for the ordinary population. However, the researchers soon had the feeling that this result was due to the small sample size. Studies in larger populations have shown that men with an unconventional set of chromosomes are no more likely to commit violent acts than those with a normal set. Psychological theory. Psychological theories of crime, like biological ones, link criminal propensities with a certain personality type. In the 20th century, some psychologists, building on the ideas of Sigmund Freud, suggested that a small number of people developed an “immoral” or psychopathic personality. According to Freud, most of our moral qualities derive from self-control, which we learn in early childhood. Due to the special nature of the relationship with parents, some children do not develop such self-limitations and, as a result, there is no basic moral sense. Psychopaths can be described as autonomous people who take pleasure in violence as such. Psychological theories of crime have, unlike biological ones, a rational grain. However, at best, they can only explain some aspects of crimes. Although an insignificant minority of criminals have personal characteristics different from the rest of the population, such characteristics are not inherent in all lawbreakers.