Personality: this is how it is formed!

The character is not fixed. It develops throughout childhood from innate characteristics, modulated by the influence of the environment.

Jim Lewis and Jim Springer were separated at birth. When these twins found each other forty years later, they realized that they had given the same first name to their sons, that they drove light blue Chevrolets, had exercised both the profession of sheriff and liked the same brand of beer… Surprising coincidences or proof that some of our tastes are inscribed in our genes? Not easy, since it is enough to confront the destinies of another pair of twins to, conversely, point out the differences. Monozygotic twins who inherit the same genetic heritage fascinate scientists. Comparing their trajectories makes it possible to see a little more clearly between what is innate and what is acquired.

It is the temperament and the character that form the personality

According to psychologists, our personality is a subtle alchemy between five dimensions: extroversion (go-getter, talkative, enthusiastic), openness (curious, imaginative), agreeableness (compassionate, caring), neuroticism (choleric, anxious) and “conscientiousness” (organized, rigorous). Everyone possesses these traits but in varying doses, and it is their combination that makes us unique. Scientists distinguish between temperament, a baggage provided largely from birth, and character, which is acquired throughout life; both forming the personality. “The traits that define a temperament are mainly influenced by biological factors and they remain fairly stable over the course of a lifetime”, explains PrDiane Purper-Ouakil, psychiatrist at the Montpellier University Hospital, in Hérault.

Part of the personality is engraved in the genes, received from the parents. In 2006, American psychiatrist David Rettew, from the University of Vermont, conducted several studies with twins aged 12 to 18. He showed that genetic factors explain 59% of neuroticism, while the environment (the environment, food, pollution, etc.) contributes 41%. Same results for extraversion with a slightly higher proportion of genetic factors. Overall, personality traits are 50% dependent on genetic factors. This part loses ground over the course of childhood. Thus, for shyness, there is equality in the baby: half genetic, half environment; in children, genetics only weighs 24%. Because as the child grows, he is subject to several models (parents, friends, teachers…).

Testing >> Which expression best defines your character?

Genes are not responsible for everything

Nothing is therefore played in advance. “Genes are not responsible for everything, far from it,” warns Patrice Bourgeois, doctor of science at Marseille’s public assistance and author of the genetics for dummies (First ed.). Since the 2000s, the weight of genetic inheritance has been put into perspective, thanks in particular to the discovery of epigenetics. Indeed, researchers in biology have demonstrated that our environment modifies the expression of our genes. Our life, our experience shape not their nature but the way they express themselves. Different phenomena come into play, including methylation, a biochemical process essential to the body: small blocks of molecules, called methyl groups, are grafted onto the DNA, preventing it from being read in one place (or conversely, the allowing), much like a Scotch tape applied to a magnetic tape. This explains whether a gene is activated or not.

Biological, educational or social factors are intimately intertwined

These changes can affect the construction of the personality. For example, early affective deficiencies can modify the expression of certain genes and be the cause of anxious or even depressive personalities. Pregnancy also plays an essential role. In 2017, researchers from Kings College, London (England), studied the fetal DNA of more than 300 babies who had become adults: 54% had experienced behavioral problems between 4 and 13 years old. Among them, half had lost these attitudes in adolescence—the others having become antisocial adults. By comparing the DNA of aggressive children with that of others, researchers have highlighted differences in methylation—marks that appeared due to alcohol or tobacco consumption by the mother during pregnancy. On the other hand, they did not discover any difference in gene expression between those who retained these disorders in adulthood and those for whom everything was settled in adolescence. The latter have undoubtedly grown up in a more favorable environment, which shows the extent to which biological, educational or social factors are intertwined. “We think that individual characteristics develop more or less precociously, in the interaction between genes and the environment. The distinction between innate and acquired has lead in the wing, “says PrPurper-Ouakil.

Descendants of Holocaust survivors are more prone to stress

Are epigenetic marks transmitted over several generations? Sometimes yes. In 2013, a study found that this is the case in mice. Male rodents subjected to stress — an odor associated with an electric shock — passed on the fear of this fragrance via their sperm to the next two generations. In humans, it has been shown that the descendants of Holocaust survivors are more prone to stress, in particular due to low cortisol levels, which disrupts the physiological circuit for managing anxiety.

Our character takes years to forge

The construction of the personality does not pass only by the genome associated with the epigenome. “We humans are very slow learners compared to some animal species. Our character therefore takes years to be forged,” explains PrPurper-Ouakil. Do parents play a leading role? The answer remains unclear: Studies of children adopted and raised as siblings reveal that they share few character traits. And in adolescence, the parental imprint diminishes. During this period, brain maturation intensifies and the teenager gets closer to friends with similar temperaments, which further strengthens his traits.

Impossible to shape the personality of a child in his own image!

Faced with the force of biology and in competition with other influences, what can parents do? Impossible to shape the personality of a child in his own image! “Observing your child acting, without intervening and without any particular intention, is part of the exercises during our workshops,” says Béatrice Grumler, trainer in positive discipline and parenting. The parents then discover in their offspring unsuspected skills that they can help them develop. According to PrPurper-Ouakil, in the event of a difficult temperament, an appropriate education makes it possible to avoid the development of pathological disorders. To encourage motivation, perseverance, self-control, parents remain the first role models. They also play a key role in building self-confidence. Numerous studies have shown that they must provide attentive and warm supervision, accompanied by firm and consistent discipline, while communicating with their children. But leading by example is not always enough. “Parents devoted to a cause can fail in their mission, warns psychologist Chantal Rialland. If the children have felt deprived of their parents’ love because of their commitment, the transmission may not go well. Whatever the weight of the parental heritage, nothing is therefore completely inscribed in the genes or the brain. Everyone keeps the levers to make it grow or, on the contrary, try to modify it.

Cécile Coumau and Caroline Peneau

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Personality: this is how it is formed!