The Genetics of Human Behavior

Genetics is, relatively speaking, a very young science. After the discovery of DNA several decades ago, it ceased to be exclusively a statistical and psychological study of heredity and has since acquired a key component in its laboratories: the microscope. In simple words, we are now able to dive more deeply into the world of genes and their government of the human body and behavior. In this short time we learned a great deal about human genetics and how it works. We have already identified many genes that influence our behavior and interactions with others and our environment. Let's discuss some of the genes that have already earned intriguing nicknames based on their capabilities or the functions we suspect they perform.

The mixture of genes we own is given to us by our parents, who inherited them from their parents, who were gifted with the same from their mothers and fathers, and so on. What our DNA ultimately consists of is what we like to call the genetic lottery. It essentially defines us, influencing not only our appearance and physical traits but also our behavior. For example, some of us have a dominant 'wanderlust gene' that drives individuals toward adventurous behavior, an everlasting desire for travel, and a quest for the unknown. The other example is a 'warrior gene', which in many cases explains somebody's aggressiveness and violent behavior. There's even a 'god gene', a molecule identified with a power to direct a person to be superstitious and religious. Imagine what happens if these three genes become dominant in a single person who, by chance, becomes the leader with worldwide influence.

The main question regarding human behavior is whether the environment or a person's genetics has a dominant influence. The best answers, of course, are given by a statistical study of separated identical twins who, after reunion, showed many similarities in personalities even though they were raised in different families and environments. However, we should also recognize the important influence of the environment, because although complex multiple genes determine our behavior, environmental influences can to some extent mask their effect. For example, even if you have a warrior gene, its influence could be buried if you are raised in a loving family without much violent disturbance from the others. Additionally, in many scenarios, the influence of the warrior gene could be more positive than negative; for instance, in your sports career, it is often beneficial to exhibit a certain level of allowed aggressiveness.

With the disclaimer that I am not a genetics specialist, please find additional information in the referral links throughout this page. Having said that, allow me to introduce half a dozen identified genes, or candidates in many cases, that are responsible for various key human characteristics.

Wanderlust gene
DRD4-7R
The key word here is dopamine, a hormone and neurotransmitter responsible for many different features in our brain (including autonomous movement of muscles). However, in this particular case, dopamine is released in hedonistic situations, when we experience something enjoyable and pleasurable. The more hedonistic we are, the smaller an event or thing can trigger enough dopamine release in our brain, such as tasting a pleasant food, reading a book, or looking at a photograph. Other people have lower sensitivity to dopamine, and for those (up to 20% of the population) who contain the DRD4-7R gene, which is a variant of the DRD4 dopamine receptor, eating pleasurable chocolate is not enough to release the level of dopamine to receive a hedonistic reward. These people always seek more from their environment because they need more stimulation to hit a satisfying level of dopamine. If their environment is insufficient, they take risks and move to another, like nomads or the many large migrations of people in history who moved to a new area without obvious reason even though the environment they were initially inhabiting was as good as the new one. If you have ever expressed a strong desire to travel to various places regardless of the circumstances, it may be the DRD4-7R gene influencing you.

Refs:
https://www.telegraph.co.uk/travel/travel-truths/the-wanderlust-gene/
https://www.sciencenewsforstudents.org/article/explainer-what-dopamine
https://www.verdict.co.uk/drd4-7r-wanderlust-gene/
https://www.huffpost.com/entry/is-there-really-a-wanderlust-gene

Warrior gene
MAO-A
MAO (monoamine oxidase A) is the name of the enzyme that acts in nerve cells (neurons) of the brain as a recycling factor for neurotransmitters, and in the process of oxidation it breaks down serotonin, epinephrine, norepinephrine, and dopamine among all the brain chemicals it deals with. Signals transmitted by serotonin regulate mood and emotion; epinephrine and norepinephrine control the body's response to stress, while we already know that dopamine controls physical movements. The MAO-A gene is responsible for MAO regulation, and in people who have a variant of the "warrior gene" (a low-activity form of the gene called MAOA-L), less MAO is produced, which means that fewer of the neurotransmitters are broken down, which in turn leaves higher levels of unwanted neurotransmitters in the brain. Based on past studies, higher levels of these brain chemicals may produce higher levels of aggression, causing these people to feel little to no empathy and readily use antisocial behavior, including violence, to achieve their goals.

Refs:
https://en.wikipedia.org/wiki/Monoamine_oxidase_A
https://ghr.nlm.nih.gov/gene/MAOA#
https://www.psychologytoday.com/us/.../triggering-the-warrior-gene-in-villain-or-hero
https://www.sciencedaily.com/releases/2009/01/090121093343.htm

Creativity gene
COMT-DRD2
If you are able to produce something that is novel, useful, and closely related to human development, whether on an individual or societal level, you belong to the group of individuals with creative minds who have benefited from a genetic lottery. Dopamine, similar to the hedonistic process in our brain, is also the key hormone responsible for the creative process, according to several studies from previous decades. Dopamine levels in different parts of the brain improve communication between the frontal and striatal dopaminergic pathways, which is thought to help with creative thinking and feeling rewarded when something new is created or accomplished. The specific genes that help with dopamine transmission and create the right amount of dopamine for creativity are still being studied, but two genes, COMT and DRD2, show the most promise because of their individual roles and how they work together.

Refs:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3995040/
https://medicalxpress.com/news/2018-04-dopamine-producing-areas-brain-creativity.html
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4718590/

God gene
VMAT2
Unfortunately, due to the sensitive subject, research regarding spirituality is limited and was mostly conducted by a single experiment. The targets were monoamines - the main brain chemicals, including serotonin, norepinephrine, and dopamine - that are connected with regulation of fundamental functions such as mood, creativity, and motor control, like we already saw with previous genes. Monoamines are also the primary target for many antidepressant drugs and narcotics, which can cause addicts to experience transcendence or experiences that go beyond normal physical levels of existence. In a similar but much more benevolent fashion, a variation in a gene known as VMAT2, in that single study, was identified to be responsible for all test subjects who experienced self-transcendence compared to others that didn't have that particular variant. Whether or not this evidence is enough to call this gene a 'god gene' is debatable, but it does prove that brain chemicals encoded by specific genes can in fact affect the spiritual realm of people. In addition to external chemicals that might induce spiritual thinking and religious experiences, we also should not exclude parasitic influences such as Toxoplasma gondii, which I already mentioned in the post Who's Behind the Wheel?

Refs:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2262126/
https://www.newscientist.com/article/dn7147-genes-contribute-to-religious-inclination/
https://en.wikipedia.org/wiki/God_gene
http://www.qcc.cuny.edu/socialSciences/ppecorino/.../Genetic-Basis-for-Religion.htm

Love gene
OXT
Hypothalamus activity includes the production of the hormone oxytocin encoded by the OXT gene. The 'love hormone', as it was named after its features and properties, is also linked to social behavior. Activity of the OXT gene and production of the hormone can vary from person to person, and those with low activity struggle more to identify the emotional expressions of others, including people in their relationships and family members. Perhaps more than with other genes, OXT is tested in correlation to the process called DNA methylation, in which methyl groups are added to DNA segments without changing their sequence. In life, this can be triggered by environmental influences and bad lifestyle factors such as smoking or diet. In turn, when methylation increases on the OXT gene, less oxytocin is produced, and this impacts social behavior for the worse. Like with anything else, and especially with genetics, balance could be the key word, and further research could lead to potential treatments that could effectively fix social disorders.

Refs:
https://www.voanews.com/a/mht-love-hormone-gene...oxt-oxytocin/3387692.html
https://www.techtimes.com/articles/...people-form-healthy-lasting-relationships-study.htm
https://en.wikipedia.org/wiki/Oxytocin

Mad Scientist gene
DARPP-32
The coolest name for the gene goes to... DARPP-32, a variation within a gene that, not surprisingly, is also capable of affecting levels of the dopamine hormone, this time in the area that influences feelings of anger and aggression. The twist with this gene is in the fact that a particular variant is also associated with increased performance in a number of cognitive tests, including IQ and memory. Actually, three out of four people inherit a version of the DARPP-32 gene, which, by improving information processing in the prefrontal cortex of the brain, in simple words, allows and improves the brain's ability to think. These two effects combined will not give us mad scientists per se, but they do explain the strange behavior and fears of some people with high IQs from the past. I am not saying that Tesla's strange fear of shaking hands or Einstein's hatred for socks is granted by this gene, but I am sure the genetic lottery in one way or another is the one to blame in a high percentage.

Refs:
https://www.bionews.org.uk/page_91056
https://www.elitedaily.com/life/culture/genius-little-crazy/995625
https://www.medicaldaily.com/.../mad-scientist-stereotype
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1784004/

Smoking and drinking genes
CHRNA5, OPRM1
There are several genes associated with smoking, nicotine dependence, and lung cancer, but among them the variant of CHRNA5 is the most prominent candidate. The process is identified as nicotine-stimulated dopamine release in the striatum (a cluster of neurons in the subcortical basal ganglia of the forebrain), a region vital to the development of substance dependence but also a reward learning center. Combined, people with this particular variant are more likely to overcome casual and environmental intake of nicotine and become heavily addicted to smoking. Similarly, the OPRM1 gene has been associated with subjective responses to alcohol in heavy drinkers. The 'G variant' of this gene may lead to a greater susceptibility not only to addiction to alcohol but also to variations in pain sensitivity and addiction to opioid substances.

Refs:
https://www.sciencedirect.com/topics/neuroscience/chrna5
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4000030/
https://www.ncbi.nlm.nih.gov/pubmed/23240711
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5152594/
https://drbrucekehr.com/oprm1-gene-test-addiction-genetic-testing/

In conclusion, let's get back to the beginning: genetics and especially the study of human behavior are merely at the beginning of understanding all the processes that govern our brain on the smallest levels within organic chemistry. However, we don't need any science to attribute human behavior with a strange ability to give nicknames to everything and anything. Genes are no exceptions, and hopefully you have identified some of them shaping who you are and how you behave.

Image refs:
https://www.eturbonews.com/238528/non-stop-travel-destinations-for-the-adventurous/
http://knrunity.com/post/general/2016/post-787.php
https://www.askmen.com/sports/bodybuilding/warrior-based-training.html
https://blog.lifeway.com/explorethebible/blog/why-young-adults-need-bible-skills/
https://www.thebump.com/a/ways-for-dad-to-bond-with-baby
https://www.inverse.com/article/7576-best-mad-scientists
https://coach.nine.com.au/latest/red-wine-and-smoking/

Refs:
https://www.psychologytoday.com/us/blog/.../what-behaviors-do-we-inherit-genes
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3052688/
https://www.khanacademy.org/science/ap-biology/heredity/environmental-effects-on-phenotype/a/genes-environment-and-behavior
https://en.wikipedia.org/wiki/Twin_study