science behind criminals

1. Are Criminals Biologically
Determined?
Madelyn Carter
8 Nov. 2021

2. Introduction
● Centuries ago, doctors performed
lobotomies on criminals,
believing it would “cure” the
offenders as their wrongdoings
were caused by a brain mutation.
● That procedure is no longer
practiced since the nature versus
nurture debate was unveiled.
● While the MAOA gene does cause adulthood aggression, the cause of
criminal acts is a mix between nature and nurture because people
who have a perfect homelife still commit crimes and people with
horrible upbringings do not always resort to criminal activity.

3. Nature
● Psychophysiology
○ Study of the interrelationships between
mind and body
● Blunted Autonomic Functioning
○ Weak nervous system
○ Interferes with body reactions
○ Can lead to increased antisocial behavior
which is often a trait in criminals

4. Hypothesis
● Fearlessness Hypothesis
○ Individuals don't deter from criminal acts because they do not have the
appropriate mind and body responses to risky situations nor do they realize the
potential consequences.
● Sensation-seeking Hypothesis
○ The blunted state of being is uncomfortable so the individual tries to compensate
for the lack of emotion and reaction by engaging in inappropriate acts.
● Somatic marker Hypothesis
○ “Somatic markers” such as sweaty palms, reveal emotions and can change the
decision making process.

5. Nurture
● Abuse and trauma
○ How a child reacts to abuse determines what they’ll do with their trauma,
such as reacting with anger or trying to make the world a better place.
● Media
○ The media has made this topic more of a cultural issue rather than a scientific
one, also turning it into a larger issue than need be.
● Civilian study
○ In a conducted study, civilians stated they believe that society, politics and
life affects the way an individual grows and adjusts throughout life,
psychologically.

6. “Serial Killer Gene”
● Mental disorder
○ Most people that the so called “genetic marker” is a mental
disorder, after all there was a study that showed that a high
number of criminals with the most violent crimes had mental
disorders.
● Predisposition
○ There is a certain type of gene that only exist in abused
children, it is believed to predispose a person to criminal
behavior.
● MAOA
○ The common misunderstood “killer gene,” is actually just an
aggression gene. The higher the levels, the lower the
aggression. It's believed to be the “most common denominator
in a criminal’s mind.”

7. Infamous Killers
● Bobby Joe Long
○ Has an extra X chromosome, causes him to make excess estrogen.
● Israel Keyes
○ Loved violence and to torture anything with a heartbeat, a believed psychopathic trait.
● Michael Madison
○ Suffered constant abuse from his mother and her boyfriends. The lack of nurturing and
love in his childhood led him to create another world for himself where he could take
control.
● Ted Bundy
○ Often believed to be psychotic, which was found to be false, he actually suffered from
severe bipolar disorder and showed low levels of MAOA gene activity.
● Jeffrey Dahmer
○ Childhood trauma that led him to grow distrustful

8. Conclusion
● In conclusion, a mixture between nature and nurture causes an
individual to commit criminal acts.
● Still, this controversial topic remains unsettled. With so many factors
playing into a person’s development, it is difficult to find a true
reasoning behind criminality.

9. Sources
● “Biological Risks Factors for Involvement of Crime.” The Ministry of Justice. Mar. 2009,
https://www.beehive.govt.nz/sites/default/files/Biological%20Risk%20Factors.pdf. Accessed
24 Sept. 2021.
● “Do Serial Killers Have an Extra Chromosome?“ The University of Melbourne. 30 Sep. 2014,
https://blogs.unimelb.edu.au/sciencecommunication/2014/09/30/do-serial-killers-have-an-
extra-chromosome/. Accessed 23 Sept. 2021.
● Hernandez, Jose, et al. “Nature (MAOA) and Nurture in a Criminal.” UC Merced Undergraduate
Research Journal. 2015, https://escholarship.org/uc/item/5w51b7bg. 25 Sep. 2021.
● Jones, Dan. “What Makes a Criminal?” New Scientist, vol. 247, no. 3290, July 2020, pp. 42–45.
EBSCOhost, doi:10.1016/s0262-4079(20)31213-6.
● Ling, Shichun, et al. “Biological Explanations of Criminal Behavior.” Psychology, Crime & Law:
PC & L, vol. 25, no. 6, 2019, pp. 626-640. doi:10.1080/1068316X.2019.1572753.
● Locker, Melissa. “American Psychos: 10 Modern Serial Killers You’ve Never Heard of.” Rolling
Stone. 1 Aug. 2016, https://www.rollingstone.com/culture/culture-lists/american- psychos-10-
modern -serial-killers-youve-never-heard-of-102597/israel-keyes-103521/. Accessed 29 Oct.
2021.
● “What Influences Criminal Behavior?” Walden University, 2021, https://www.waldenu.edu/
online-bachelors-programs/bs-in-criminal-justice/resource/what-influences-criminal-behavior.
Accessed 23 Sept. 2021.