According to theU.
S. National Library of Medicine, a gene is the most basic physical andfictional unit of heredity (“What is a Gene,” 2017) and they make us who we are.A genetic description would say that within a person’s genetic makeup, theremight be crime genes that generate a tendency for crime. There are many debatesaround the idea about how a person’s genotype can play a significant role inthe development of your personality, but especially relating to criminality. Researchhas been done to show that inherited genetic predispositions may correlate withthe risk of developing criminal behavior. Many believe that the environmentthat surrounds you shapes how you are, but can your genes predict your criminalbehavior? An example of apossible genetic abnormality leading to criminality would be the XYY karyotype.
It was once thought that males with an extra Y chromosome (XYY males) exhibitedgreater criminal behavior and are more prone to aggressive behavior than XYmales. This claim about the XYY karyotype is part of the “Nature vs. Nurture”debate. The belief that nature, or the biological determinism and inheritanceis more important than the effects of the environment and education was thebasic idea of “eugenics” coined in by Francis Galton (1822-1911). Eugenics isthe set of beliefs and practices which aims at improving the overall geneticquality of the human population, by discouraging the reproduction of peoplewith genetic defects or undesirable traits. According to Galton himself,talent, character, intellect and physical features like height, eye color areall governed by heredity.
Analogously, a tendency to develop criminal behavior,alcoholism is inherited as well. This concept however is supported by the oldconcept that biology is destiny. According toScience Clarified, about 1 in 1000 newborns males with two Y chromosomes otherthan just one, is known as the 47, XYY karyotype. This is the result of errorsthat occur in the formation of the sperm cells (paternal meioticnondisjunction) or when the fertilized egg begins to divide (post fertilizationerrors).
Unlike many autosomal chromosome irregularities, the XYY karyotype isnot linked with advancing maternal age and advancing paternal age has little tono effect either. About 80% of males with two Y chromosomes have the 47, XYYchromosome composition. Even some men diagnosed with XYY, have mosaicchromosome structures with some of their cells as 46, XY and other are 47, XYY.During the 70s and 80s, those individuals diagnosed early as fetuses wereassociated with criminal behavior leading many parents to abort. As timepassed, induced abortions decreased as further studies discredited the originalclaim. Babies born with XYY, are of normal weight and length but as they agethey develop delayed speech development and have certain behavior and learningproblems.
When the XYYtype was discovered, some researchers thought the presence of an extra Y chromosomewould make males more aggressive and prone to developing criminal behavior.This condition was termed “supermale syndrome.” XYY men have been a maininterest of psychologists and criminologist especially in prison system andafter evaluation of psychological tests, XYY males do exhibit more aggressivebehaviors than XY males. XYY males have a more rigid way of thinking and findit harder to control oneself, all leading to an aggressive-like behavior. Withhigher levels of testosterone, aggression is correlated as a result. XYY maleshave aggressive tendencies but don’t necessarily manifest in violent behaviortoward other people.