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The Biological Causes of Crimes and the Eugenics' Theory

What exactly triggers criminal behaviors? Is it genes, brain structures, neurotransmitters, hormones, etc.?

Studies show that people who consistently show both irresponsible and criminal behaviors often have both neurological and biological abnormalities that contribute to these types of behaviors (Allen Garland E., 2001). Criminal behavior is one of the most interesting topics in the field of psychology. Many experts believe that both environmental factors, as well as genetic factors, play an important role in a person criminal and antisocial behaviors.

Such argument, of course, revives the old debate of nature versus nurture that’s been around for decades. Many among those experts argue that there is evidence that proves a person’s genetic makeup (code) is somewhat responsible for his/her criminal behaviors. While others argued that environmental factors are very determinant in a person developing criminal/antisocial behaviors. So who's wrong and who's right?

Well, the truth is that both genetic and environmental factors do play an important role in a person’s criminal or anti-social behaviors. The evidence for such a conclusion has been supported by many research studies conducted on twins, families, adopted children as well as laboratory experiments.

Their finding is that there is indeed an interaction between genes and the environment that can predict both criminal and antisocial behaviors of an individual.

In other words; biological forces can act upon psychosocial factors and generate a certain type of behavior, such as criminal or antisocial ones. With that says, biological causes can be blamed for certain crimes but not all crimes.

But, why some people are still troubled by the idea that crime may have biological causes?

There are various reasons why some people might still have great difficulty to accept the idea that crime has biological causes:

1) First, researches prove that genes are ruled by the environment rather than the environment being ruled by genes. This means; a person’s environment can either mute or aggravate violent impulse.

A person's genetic code is what makes him/her who he/she is and it is also what makes him/her very unique from others. If a person's genetic code already has criminal and antisocial traits in it, and he/she finds himself/herself in an environment where psychosocial factors that can trigger criminal or antisocial behaviors are present, the chance for him/her to become a career criminal is very high.

However, those researchers conjointly go further more to prove that many people with the same genetic tendency for aggressiveness will never throw a punch at someone throughout their life span, depending on where they live and who they surround themselves with. While others who are without any sign of aggressiveness can easily become career criminals right under everyone's eyes, but no one would've never thought about it until they get caught on the act.

2) Second, many believe that the victims of those violent crimes committed by certain criminals should not suffer twice for behaviors they are not responsible for, so letting criminals go free in the concept of being mentally ill is encouraging the repetition of that same behavior in the future (Unnever James D. et al., 2008).

3) Thirdly, people don’t really believe that many of those who commit crimes are insane or mentally ill. They believe that, this is nothing but excuses and that they should still be held accountable for their actions. So to conclude, there is a vast majority of people who believe that the idea of crime has a biological cause is just a way to beat the justice system, that crimes remain crimes regardless of both environmental and genetic factors' argument.

(The Eugenics' Theory and the Movement)

Eugenics movement is the study of or belief in the possibility of improving the qualities of the human species or a human population, especially by such means as discouraging reproduction by persons having genetic defects or presumed to have inheritable undesirable traits or negative eugenics, or encouraging reproduction by persons presumed to have inheritable desirable traits or positive eugenics. Through the eugenics movement, genes were categorized as fitted genes or unfitted genes.

This theory was first established by Sir Francis Galton in 1883 based on his half cousin’s theory of evolution, Charles Darwin (Gillham Nicolas W., 2001).

The plan of the eugenics movement was that, since most crimes are committing among and by the poor, the poor definitely inherited these genes for feeblemindedness, that’s what led them to misery, vice, crime, etc. According to Francis F., the obvious solution to American social problems was to sterilize those with these types of genes and restrict the immigration of more poor and their repopulation in the country (Gillham Nicolas W., 2001). The Eugenics movement was way too radical and it failed to bring any durable solution to the biological cause of crime.

The reason is simple, we can’t possibly categorize a whole group of people as being responsible for crimes and any other antisocial behaviors simply because of their social status. Of course, there are more crimes among the poor and there will always be more crimes among them because they lack financial and social resources.

By no mean, I’m encouraging such behavior, but before categorizing or labeling a whole group of people or a race as “unfit” it would be wise to first, remove them from their actual environment and social status (poverty) and observe if there would be any modification in their antisocial or criminal behaviors.

Francis Galton’s theory, which is the eugenics system failed to solve or reduce crime or modify any form of antisocial behavior. So my conclusion is that there’s no relationship whatsoever between the biological cause of crime, its solution, and the eugenics movement. In fact, the eugenics movement, in my opinion, was a crime on minorities (the poor).


Allen Garland E., (2001), Historical Studies in the Physical and Biological Sciences: The biological basis of crime: An historical and methodological study. Data Retrieved from:

Argosy University, (2014), Criminology (For Class PSY3XX Introduction to Crime & Causes), 10th Edition: Biological and Psychological Explanations of Crime. Data Retrieved from:

Gillham Nicolas W., (2001), Annual Review of Genetics: Sir Francis Galton and the Birth of Eugenics. Data Retrieved from:

Unnever James D. et al., (2008), Sociological Focus: Public Support for Attacking the "Root Causes" of Crime: The Impact of Egalitarian and Racial Beliefs. Data Retrieved from:

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