Do your genes determine your life choices?

© The New York Times

Leviathan Press:

In recent years, researchers have discovered that the formation of new memories is accompanied by some epigenetic changes . For example, the DNA helical structure in neurons is rearranged and new methylation patterns are established. However, the plasticity of the epigenome is not all beneficial. Some studies have shown that stress and other negative influences may change the epigenetic patterns in our cells, causing long-term damage.

One of the strongest pieces of evidence for this connection comes from Michael Meaney’s lab at McGill University. In the 1990s, Meaney and his colleagues began a study to understand how rats experience stress. They put rats in a small plastic box, where the animals became anxious and produced hormones that raise their pulses. Some rats responded to stress more strongly than others. It turns out that the rats that produced more stress hormones were licked less by their mothers as pups. This means that when mothers lick their pups, the experience changes neurons in the hippocampus: some of the methylation around their receptor genes is removed. Freed from the influence of the methylation, the genes become more active and the neurons produce more receptors. In the pups that were licked well, these neurons became more sensitive to stress and were able to manage it more effectively. Rats that were licked less often developed fewer receptors. They eventually became overly stressed.

(https://pubmed.ncbi.nlm.nih.gov/16262207/)

Given that rats and humans are both mammals, children may also experience long-term changes in stress levels depending on the environment they are raised in. In a small study, Meaney and his colleagues examined brain tissue from human cadavers. They selected 12 people who had died of natural causes, 12 who had committed suicide, and another 12 who had committed suicide after experiencing childhood abuse.

(www.newscientist.com/article/mg20126974-700-child-abuse-may-leave-suicide-marks-on-genes/)

Meaney and his colleagues found that those who experienced childhood abuse had relatively more methylated groups around receptor genes in their brains, just like the rats that were licked less. Just as these rats produced fewer stress hormone receptors, the neurons of individuals who were abused as children also had fewer receptors. It is conceivable that childhood abuse led to epigenetic changes that altered mood in adulthood, which then snowballed into suicidal tendencies.

Deep underground in a granite building on the outskirts of Reykjavik, the capital of Iceland, a robot is slowly and methodically moving the cold blood of tens of thousands of people from all over the world.

A meticulous experiment is underway in this concrete chamber. DNA is extracted from a sample and fed into a sequencing machine, which slowly pieces together the unique sequence of chemical bases that underlie each person’s identity. Later, artificial intelligence algorithms will tie this genetic code, or genome, to detailed information about these people’s lives stored in the biobank—their diets, personalities, relationships, hobbies, and eventually diseases they contracted—looking for what scientists believe are likely statistically significant connections.

This particular concrete chamber is owned by an Icelandic company called deCODE genetics, which has sequenced more than 400,000 whole genomes and counting, more than any other institution in the world. In doing so, it has made significant contributions to our understanding of human genetic risk for Alzheimer’s, schizophrenia, coronary heart disease, various forms of cancer, and many other chronic diseases[1][2].

It has also inspired the study of human psychology through sequencing, trying to find links between our genome and our personality, food preferences and even our ability to maintain relationships.

This type of research is not just about developing new drugs, but more importantly, it is about revealing new links between the genome and our life choices. For many scientists, this is a new topic: to what extent our behavior is the product of our own will and to what extent it is predetermined by biological characteristics?

"As a species, our existence is based on the information in our genome, which interacts with the environment," said Kári Stefánsso, an Icelandic scientist who founded deCODE genetics in 1996 with the original goal of using Iceland's unique genetic situation to learn more about common diseases. Iceland's small population and centuries of relative isolation mean that there are far fewer genetic variations than in other countries. Relatively speaking, there are fewer factors that complicate research, making it easier for scientists to identify meaningful genetic variants.

© David Grey/Reuters

Stephenson, a 73-year-old neuroscientist and philosopher, is increasingly convinced that the complex mix of DNA we inherit from our parents and the 70 or so spontaneous gene mutations we acquire by chance[3] subconsciously govern our behavior far more than we realize.

We may not realise it, but many of the mundane things we do in our daily lives may be driven in part by our genome. Subtle genetic tweaks in our taste receptors determine whether you prefer coffee or tea. It turns out [4] that coffee lovers are less sensitive to the bitter taste of caffeine, while tea lovers are less sensitive to other types of bitter chemicals.

Genetics also play a role when it comes to our love or aversion to exercise. Put simply, it determines how much you enjoy exercising[5], as well as whether you prefer more solitary sports such as running, or whether you prefer to compete with others as part of a team sport. At the same time, DNA can also specifically influence our leisure interests.

The possibility of a hobby gene was first suggested 15 years ago in a survey of 2,000 British adults.[6] A look at their family trees and the pastimes enjoyed by their ancestors revealed strong inclinations toward certain types of activities. Survey participants were often surprised to discover that their ancestors were actually amateur gardeners, stamp collectors or bakers.

Over the next decade, many people around the world have mentioned this research, as they discovered that they suddenly had an inexplicable interest in the hobbies of their parents or grandparents in adulthood. Michael Woronko, an insurance worker from Ottawa, Canada, wrote on Medium, "Even when my mom dragged me to her community garden as a child, I never showed any interest in gardening. I was not interested in hybrid tomatoes, sprouting peppers, etc., but at some point in adulthood, something jumped out from deep inside of me and I fell in love with gardening. "

Large-scale genome sequencing studies are unraveling mysteries. Stephenson says deCODE scientists have even discovered a specific gene variant that determines whether or not you’ll be drawn to crossword puzzles. “We know that if you have this gene, you’ll enjoy crossword puzzles, regardless of whether or not you’re good at them,” he says with a laugh.

Genome sequencing is also effective when it comes to the complex question of how our genes determine our life paths.

© SciTechDaily

From Boston to Shenzhen, tech startups have spent years searching for so-called talent genes, genetic variants that might give a person an innate strength or unique language ability, allowing them to be guided toward areas where they can be most valuable.

But it's not as simple as it seems.

Geneticists at the Max Planck Institute in Leipzig, Germany, recently tried to link a gene called ROBO1, which controls the development of gray matter in parts of the brain involved in representing numbers, to children’s mathematical abilities.[7] But so far, it seems that genes have only a relatively small influence on all talents, whether it’s number crunching, musical ability, or athleticism.

Instead, as Stephenson discovered with the crossword puzzle, our genes seem to influence our propensity to perform certain activities. * What really determines whether we are capable of learning is whether we receive instruction as children and our own willingness to practice, improve, and persist.

The latter points to where genetics may have the most significant influence on our life paths: our personality traits. Danielle Dick, a professor of psychiatry at Rutgers University in New Jersey and author of The Child Code, argues that large parts of personality, such as extroversion or introversion, conscientiousness, agreeableness, impulsivity, and even our creativity, have some genetic component .[8][9][10]

"This reflects the fact that our genes influence the way our brains are shaped, which in turn influences the way we think and interact with the world," Dick said. "Some people's brains are wired to seek excitement or novel experiences, to be more able to take risks, or to be attracted to more immediate rewards."

© Tenor

These traits can be advantages. Entrepreneurs, CEOs, fighter pilots, and extreme sports athletes are all natural risk takers. But having these genes may come at a cost. Stephenson’s research shows that risk takers are more likely to become addicted,[11] and that some people with genes that encourage creative thinking actually develop schizophrenia.[12] People who are naturally impulsive may be better decision makers, willing to seize opportunities that would otherwise pass them by, but they are also more likely to have problems with gambling, drop out of school, or get fired.

Our genes influence the way our brains are formed, which in turn influences the way we think and interact with the world. —Danielle Dick

Dick recently co-authored a study[13] that used data from about 1.5 million people to identify genetic variants associated with impulsivity. She found that impulsive people tend to be more likely to develop attention deficit hyperactivity disorder (ADHD) as children, or to smoke and use drugs in adolescence and adulthood, and later develop related symptoms such as obesity and cancer.

"What remains clear, though, is that DNA is not destiny," Dick said. "Our genes influence our personalities and our natural tendencies, but that doesn't mean that people with those genes will always have problems. "

Stephenson, the founder of Decoding Genetics, believes that DNA subconsciously controls our behavior more than we realize. © Alexander Mahmoud/Alamy

The environment we live in is very important in determining whether we act on our genetic predispositions. Stephenson says that people who have a gene variant in their brain that causes them to have low self-control are more likely to overeat if they work next to a fast food restaurant, and find it difficult to quit smoking if they start smoking. At the same time, there is evidence that having a stable family life, stable relationships and friendships, and even regular exercise can help them live a meaningful life.[14][15]

“The people who are most at risk are also the ones who benefit the most from a healthy environment,” said Cecilia Flores, a professor of psychiatry at McGill University in Canada. “A positive environment can buffer genetic susceptibility or even reverse it.”

Not only does this help explain the link between personality and addictive behavior, social scientists are also finding that studying this type of gene-environment interaction can explain why some people are better suited to maintaining long-term relationships than others.

Love Gene

Four years ago, sociologists at the Yale School of Public Health began a study of 178 couples aged between 37 and 90.[16] Each couple was asked to answer questions about their feelings of happiness and security in their marriage and to provide a saliva sample for analysis of certain genes.

Early research suggests that genes play a role in our choice of friends and even our choice of partners. In both cases, we tend to form attachments with people who share some physical similarities with ourselves. “We tend to form social relationships with people who are more genetically similar to us,” says Andrew Dewan, a genetic epidemiologist at Yale University. “We can assume that the genes that control these traits have some influence on who we choose to form friendships with.”

© Xcode Life

It turns out that genes also play a role in our ability to maintain stable, happy relationships over the years and decades. Previous research has shown that children of divorced parents are more likely to divorce[17]. The Yale study investigated the role of oxytocin, a hormone that makes couples feel closer to each other. When at least one partner in a marriage has a certain gene variant that increases oxytocin activity and makes the brain more receptive to its benefits, such partners are less likely to show psychological symptoms known as anxious attachment, and the couples are happier.

Anxious attachment is a specific type of relationship insecurity that stems from past experiences with close family members and former partners and leads to low self-worth, a heightened sensitivity to rejection, and a desire for approval. "This suggests that inherited genetic variation can influence how happy we are in our relationships," Dewan said. " Genes don't completely determine our ability to form long-term relationships, but they are a contributing factor that may push us in one direction or another, either toward or away from it. "

Genes determine how much you like to exercise, and whether you prefer more solitary physical activities such as running. @Alamy

In the fields of medicine and psychology, psychiatrists, child development experts and obesity specialists are hoping to use the increasing amount of genetic information to formulate public health policies and provide practical advice to people.

Nicola Pirastu, a biostatistician at the Human Technopole research institute in Italy, has found that genetic variants in food preferences can shift our preferences from fruits and vegetables to high-calorie, high-fat foods.[18] Because many of these variants are found in the brain, he argues that obesity should be considered a disease that needs to be treated with drugs rather than dietary interventions.

"Losing weight is very difficult," he said. "It's not just a matter of willpower. If you're always hungry, of course you want to eat. So, medication to reduce food cravings can work. Of course, you can also do it with diet, but it's like a full-time job and few people can do it."

As the cost of gene sequencing continues to drop, it could be used in the future to screen children or adolescents for signs of addictive behavior. Dick said: "I hope that the public will understand that childhood behaviors such as addiction are often related to genes, thereby reducing the stigma of children. By screening children at risk of addiction early, we can take action to help them so that they can reach their full potential."

© CBC

Dick believes that if a person and his family can foresee that he may develop addiction or risk-taking behavior, he can actively avoid risks. But she said that society must also play its due role. She said: "Many people in the addiction research field are worried that the new laws in the United States, which make it easy for people to obtain psychotropic drugs and engage in online gambling, will promote these behaviors and lead to higher incidence of addiction."

But we are only beginning to understand how genes determine our behavior and the role they play in the choices we make in life. Over the past two decades, Stephenson and other scientists have slowly begun to make connections, but many fundamental questions remain unanswered.

“ A serious question is, can you inherit a mind? ” Stephenson asks. “Do you inherit the way you think from your parents? Perhaps the reason we can’t answer this question is that we don’t have a precise definition of what a mind is. However, if we take humans as an example, we can say that we are basically defined by our thoughts and emotions. But today in 2023, we can’t even come up with a single attribute that defines us as human. ”

References:

[1]www.nature.com/articles/nature11283

[2]www.nejm.org/doi/full/10.1056/nejmoa1508419

[3]elifesciences.org/articles/46922

[4]www.nature.com/articles/s41598-018-34713-z

[5]link.springer.com/article/10.1007/s10519-019-09990-7

[6]www.telegraph.co.uk/news/uknews/2705364/Hobbies-and-careers-are-inherited.html

[7]journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000871

[8]www.sciencedirect.com/science/article/abs/pii/S0306987721000311

[9]royalsocietypublishing.org/doi/abs/10.1098/rstb.2012.0380

[10]psycnet.apa.org/record/2016-03227-001

[11]akjournals.com/view/journals/2006/2/1/article-p1.xml

[12]www.nature.com/articles/nn.4040

[13]www.nature.com/articles/s41593-021-00908-3

[14]www.ncbi.nlm.nih.gov/pmc/articles/PMC6803054/

[15]www.ncbi.nlm.nih.gov/pmc/articles/PMC6803054/

[16]journals.plos.org/plosone/article?id=10.1371/journal.pone.0213083

[17]journals.sagepub.com/doi/abs/10.1177/0956797617734864

[18]www.nature.com/articles/s41467-022-30187-w

By David Cox

Translated by Bella

Proofreading/Rabbit's Light Footsteps

Original article/www.bbc.com/future/article/20230509-how-genetics-determine-our-life-choices

This article is based on the Creative Commons License (BY-NC) and is published by Bella on Leviathan

The article only reflects the author's views and does not necessarily represent the position of Leviathan