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

Genetic Genealogy

Recently, my five-year-old boy asked me the question I knew it would eventually come. The very question all parents are inevitably faced with when the right time comes. With my son it came in the simplest form: "What is God?" popped occasionally after tons of OMGs he heard everywhere in his realm of cartoons, video games, YouTube channels, and TV shows. I wasn't prepared completely. I mean, I had a pretty good idea of how to explain mythical phenomena, unknown and unexplainable tales, and the very concept of belief, but I didn't know how to do it without destroying Santa Claus, the Easter Bunny, and other fairy tales he enjoys every year. To me, it's much too early for that age in life. It would only add disappointment and confusion, and it's better to leave it for a little later. So I performed good old evasive maneuvers, and in a couple of curves, I succeeded in changing the topic and postponing the inevitable for the next time, which will come probably sooner than I think. The truth is, while it is not too difficult to explain the absence of God with the simple Occam's razor principle, it is extremely hard to comprehend why so many people live in their world of prayers, worshiping the divine and believing in a wide variety of religious stories.

Gene -> DNA -> Chromosome -> Cell*

To be honest, whether or not God(s) is responsible for the very creation of life as we know it or it came after a long period of evolutionary 'tries and errors', one thing is for sure. Whoever the creator is, today we know a great deal about how the life laboratory works and almost completely understand the very basics of how one living entity grows from the stage of being a small seed (or two of them, to be precise, for many species) to a fully formed individual. It's all written in the biggest molecule out there, located in every single living cell. No matter if you are a virus, small bacteria, tree, ugly fly, or any kind of mammal, how you will look and what your capacity to dazzle will be are all written in the genes of your DNA molecule. To put it simply, one gene, or a group of them, is responsible for one property of you. They are virtually responsible for the way you are smiling, how you walk, why your hair is curly and blonde, how intelligent you are, how tall you are, why you love romantic movies and hate science fiction... They even define you to be either religious or skeptic, explorer or indigenous, emotional or psychopath... Basically everything that defines a personality. You can't escape from what you are, as it is simply carved in the stone and irretrievably combined in your DNA sequence.

But how does it really work? You probably heard that human genetics are only a couple of percent different from, for example, the genetics of chimps, while the Neanderthals differ by less than one percent. In human genetics, one parent is providing 23 chromosomes that are paired with the other parent's and stored in our cells in a total of 46. Chromosome sequencing counted a sum of 32,185 genes responsible for the unique appearance of each person. There are no two identical individuals; even identical twins differ on a genetic level, providing, for example, different fingerprints among hundreds of other genetic differences they have due to mutations in genes in their early development.

Map of Human Migration**

Contrary to all those differences between individuals, genetic genealogy, on the other hand, deals with similarities and identical sequences in the human genome, trying to classify humans in their groups of origin. This scientific effort is providing a better understanding of human migrations from the point when everything started for all of us back then in Africa. Many genealogy surveys are performing DNA testing for this purpose, and after less than a decade of mass analyses of DNA material and thousands of specimens, dozens of haplogroups (geographic areas or migrational paths occupied by people with the same or similar sequences in particular genes) are identified. The evolution of humans depends on one single thing—mutations in genes or errors made in the human genome due to environmental and other factors in the long history of human migrations. Homo sapiens lived entirely in Africa 150,000 years ago and started migrating out approximately 70,000 years ago. This process is considered finished only 2,000 years ago, when the last habitable island in the Pacific was occupied. Along the way our ancestors changed according to the conditions of the area they encountered and, evolutionarily speaking, divided into different races and groups. The research so far has given us very interesting results. Probably the most valuable fact given is that we all share the same family lineage. So far, among all tested DNA samples, it is not yet identified a sample with different rooted ancestors, both male and female. This hints that all people on Earth are having the same ancestors, scientific Adam and Eve, or, to be precise, 'Y-chromosomal' Adam and 'Mitochondrial' Eve.

In other words, everyone is related, and basically, if we had the data of all people who ever lived in the world,we could be able to create one giant family tree starting with the mentioned Adam and Eve. Even though they didn't know each other and lived separately by maybe 100,000 years, those two lineages are now the only ones that have survived in time. At least until we find different data in Y-DNA and mtDNA tests and find more ancestor roots. Only to be fair, after all the testing so far, it seems that even if we find any, they would only represent the side paths and small groups of humans sharing this hypothetical lineage(s). But how exactly is it possible to trace down your ancestors by analyzing the DNA code? The goal is to identify sequences in DNA that are in a way "immune" to mutations and passed from generations to generations almost unchangeable over time. There are sequences like that in the male sex Y chromosome passed only by the father's line. More than 100 sequences and their repetitions within the chromosome have been identified over the years and are today used in searching for a match for the most recent common ancestor when two samples are compared. Those sequences in the laboratory are called markers, and the more markers are used for comparison, the more precise the result could be, meaning you would be able to find a more recent common ancestor. The same is true with the maternal lineage test; only in this case, the X chromosome is useless due to severe changes over time, and instead mitochondrial DNA (mtDNA) is used, as this is passed by female ancestors in almost unchanged form. Similar to the Y-DNA test, markers are compared, only with a difference that this time it is not the number of repetitions of sequences that are being searched for but instead predicted changes or rare mutations in DNA recombination happening over time. The same procedure can be used for testing Y-DNA as well. The combination of these two testing types and comparing the results with the sample database provide matches in both recent and ancient ancestries and predict the appropriate haplogroup for the specimen along with the list of many relatives who already tested and were found in the database.

Haplogroup I (Y-DNA) distribution

You probably noticed that I am not trying to include too much scientific data and terms. If you are eager to dive deeper into this extremely interesting research, please find links and follow-up stories I included at the end of the post. Furthermore, I am not an expert in this field, just another reader following the research for more exciting discoveries and possible breakthroughs, and not only in genetic genealogy but in general DNA sequencing as well. With the courtesy of Beth Perry Steger, my dear Facebook friend, I own an NG's Genographic testing kit, the project with probably the biggest database of tested users, counting more than half a million users. Unfortunately, due to Serbian law policy that forbids sending any kind of biological samples via any kind of mail services, I am still waiting for the opportunity to do this abroad, but nevertheless, there are only a couple of haplogroups I can belong to, and the biggest probability is the haplogroup I (M170), where almost one-third of the population of Serbs are predicted to originate from. However, there are a couple more candidates for this region of the world if we exclude possible surprises and unknown data that happened in the history of my family. Long ago I started to fill out our family tree online and only have partial data for generations 5 and above, which is too small a data specimen to conclude anything valuable. I am sure I will know more in the following years and that this post thread dedicated to genetics will get its successor.

Finally, and probably completely unrelated to the genealogy described in this post, which is more of an anthropological study and not used for medical purposes, it would be unfair, to say the least, not to mention the large percent of noncoding DNA, or "junk DNA", portion of the human genome. More than 50% of the double helix is still not fully understood. It is determined that this part of DNA is not encoding protein sequences like those genes we mentioned earlier. It seems that a big part of these DNA sequences don't have any known biological function, and only recently some new theories and studies indicate that they are very active and serve in the regulation or fine-tuning of proteins. Differences in protein regulations and molecules might be responsible for different reactions of people to the same disease. It is not clear why, for example, identical twins react differently to some infections or diseases, to the extent that in the same environments, one twin can be more immune to the same disease compared to his sibling.

Anyway, entire DNA research is still young science, and I am sure more and more discoveries are still awaiting us in the near future. To make sure we better understand what our scientists are dealing with, just try to comprehend the size of this molecule. I found the fact that one single gram of DNA can hold 700 terabytes of data while one state-of-the-art personal notebook today contains less than one terabyte of internal memory. Imagine what can be stored inside. If even a tiny portion of junk DNA is really junk, we might learn how to use it to store files inside. One day instead of magnetic hard drives, you might have a personal computer that connects to cockroaches carrying your personal data.

Guide to Finding the Best DNA Ancestry Test
https://www.innerbody.com/dna-testing/best-dna-ancestry-test

* Cell division
http://www.bbc.co.uk/schools/gcsebitesize/science/

Image follow-up stories
** https://genographic.nationalgeographic.com/human-journey/
** http://en.wikipedia.org/wiki/Haplogroup_I2_(Y-DNA)#I-L69.2
*** http://en.wikipedia.org/wiki/Haplogroup_I-M170

Refs:
https://honestproductreviews.com/best-dna-test-for-ancestry/
http://www.familytreedna.com/faq/
http://www.familytreedna.com/snps-r-us.aspx
https://genographic.nationalgeographic.com/

Wiki
http://en.wikipedia.org/wiki/DNA
http://en.wikipedia.org/wiki/Geneology
http://en.wikipedia.org/wiki/Genealogical_DNA_test
http://en.wikipedia.org/wiki/Genetic_studies_on_Serbs
http://en.wikipedia.org/wiki/Haplogroup_I2_(Y-DNA)