Where does your baby’s personality come from?

Calm or high-energy? Curious or reserved? Your child is born with their own temperament. But nothing is written in stone. While genetics are important, everything your child experiences, sees, and hears can influence them and contribute to building their character and personality, little by little.


One of a kind

From the moment your baby is born, they have their own way of reacting to situations and expressing their needs. Their temperament quickly becomes evident!

By Nathalie Vallerand

From the moment your baby is born, they have their own way of reacting to situations and expressing their needs. Their temperament quickly becomes evident!

A child’s temperament determines how they react and adapt to various situations, express and regulate their emotions, and interact with others. In short, the way your baby behaves depends largely on the temperament they were born with.

And since temperament is present from birth, it’s partly genetic. Every child’s temperament is unique.

Brothers Eliot and Zack are a good example of this. Eliot, who is 5, was a quiet baby who cried a lot and rarely smiled. “It was more difficult to connect with him,” their mother Émilie recalls. “He was born an old soul.” Zack, now 3, was a more expressive baby. He cooed a lot and smiled at anything.

Today, Zack is an adventurous little boy who loves to discover new things and finds it hard to stay put. Eliot is as serious as ever. He’s affectionate, calm, attentive, and a little shy. He also has a great attention span. The two brothers are proof of how each temperament comes with its own strengths and challenges, depending on the situation.

Your child’s temperament

Experts don’t always use the same words to explain the concept, but generally speaking, there are two defining aspects to a child’s temperament:

1- Reactivity

For example, how a child reacts to new things (food, places, people, activities, objects, etc.) is one aspect of their temperament. Are they happy, unsure, or cranky when they encounter novelty?

The ability to adapt to change also factors into the equation. Some babies adjust quickly, while others need more time. Finally, their moods are also a reflection of their temperament. Some children smile more and tend to be cheerful. Others express more difficult emotions, such as sadness, irritability, and anger.

2- Impulse control

This is a child’s ability to self-regulate, or control their behaviours, emotions, and thoughts when faced with different situations. Examples of self-regulation include resisting the temptation to touch a forbidden object, doing something they don’t really want to do, or staying still when in a public place.

It also involves their ability to concentrate and pay attention to something. For example, when your child is doing an activity that requires concentration, are they easily distracted by noises or their surroundings? Or can they remain focused for long stretches of time? Do they have trouble following rules? Their ability to control their impulses will continue to develop throughout early childhood.

Can temperament be influenced by external factors?

Ten-month-old Loïc is generally in a good mood and is always happy to discover new things. “When we take him to new places, he smiles and fidgets for us to let him go and explore,” says his dad, Jean-Sébastien.

Despite being so young, Loïc is already beginning to control some of his impulses. For example, his parents let him play with their cell phone, but they don’t let him put it in his mouth. “Recently, he’s started holding it near his mouth and looking at me, like he’s gauging my reaction,” his mother, Rachel, says.

Loïc’s temperament and the way his parents care for him influence each other. For example, research has shown that parents find it easier to be affectionate with children who are generally cheerful and follow the rules.

This reaction is understandable, since “parents of children with easy temperaments feel rewarded in a way for the care they provide,” explains Catherine Ruth Solomon Scherzer, Honorary Professor in the Department of Psychology at the Université de Montréal.

Conversely, children with more demanding temperaments (who cry a lot or throw tantrums) can discourage parents or make them more impatient. This is also a normal response, as parents can find demanding temperaments more challenging.

Even when a child’s reactions and behaviours are difficult, it’s important to remember that their temperament isn’t set in stone and doesn’t determine their future. Studies have shown that by adopting a positive attitude, parents can help their little ones improve their temperament.

Temperament evolves with experience. A child with a highly reactive temperament can learn to temper their strong emotions, providing their environment is stimulating and reassuring and they have a strong bond with their parents.

Adjusting to your child’s temperament

As a parent, your goal isn’t to erase parts of your child’s temperament. On the contrary, parents need to recognize that their child’s behavioural and emotional responses are part and parcel of their temperament. The next step is then for parents to adapt their own responses and expectations to their child’s temperament as much as possible.

“For example, it may be tempting to ignore your baby’s cries if they cry often and are difficult to console,” Ginette Dionne, a full professor at Université Laval’s School of Psychology, explains, “But a baby with this type of temperament really needs to be reassured with a quick, warm response.”

When parents respond to their baby’s needs by rocking them, rubbing their back, or cuddling with them, they’re teaching their baby that they can be trusted and are reinforcing the attachment bond. Conversely, if parents don’t respond, their baby may become increasingly irritable and impatient.

Children can learn to adapt to their environment, but parents also need to learn to adapt to their child’s temperament.

The same goes for children who throw tantrums. “If your response is to get angry, you risk encouraging their tantrums,” Solomon Scherzer continues. Instead, try to stay calm. Talk to your child once they’ve calmed down and help them put what they feel into words.

Adapting how you respond to your child’s temperament can also help better prepare them to live with others in society. This is what 5-year-old Eliot’s parents noticed when he started being afraid of new situations. Rather than being overprotective, they tried boosting his confidence by offering reassurance and encouraging him to give things a try. “Before he started skating lessons, we prepared him by explaining what would happen,” says his dad, Cédric.

His mother, Émilie, adds, “When we’re at a restaurant or with someone he doesn’t know well, we also encourage him to ask for things himself. This summer, we sent him to buy a loaf of bread on his own at the campground convenience store. He was so proud! In fact, he’s become more confident over the last few months.”

If your child has a very active temperament, make sure to give them plenty of opportunities to move around, especially before outings or activities where they’ll have to sit still. It may help them stay still when you need them to. It takes effort for little ones to stay calm and control their impulses.

Pregnancy and temperament

Many of a baby’s characteristics are developed in the womb. This holds true for both their physical and their psychological traits. Researchers at the Douglas Mental Health University Institute have found that an expecting mother’s mental health can have an impact on how her unborn baby’s genes are expressed.
A pregnant woman’s moods can affect the areas of the baby’s brain that are linked to stress and emotional control. When a pregnant woman is depressed or extremely anxious, the baby she’s carrying is more likely to suffer from anxiety, stress, and even attention deficit disorder after birth. The good news is that things can also turn around. If the mother’s health improves, and the child receives good care and grows up in a loving family, the child’s mental health is less likely to be affected.

Personality in the making

Your little one’s temperament is present from birth, but their character and personality develop over time.

Your little one’s temperament is present from birth, but their character and personality develop over time.

Character is generally defined as who we are and how we act. “Character is rooted in both a child’s temperament and their life experiences,” explains Ginette Dionne, a full professor at Université Laval’s School of Psychology. “Temperament and character rapidly converge to form a whole. It becomes difficult to separate genetics from what experiences and relationships with others add to the mix.”

For example, little Loïc is only 10 months old, but he’s already a joker. “He pretends to bite my nose because he knows I’m exaggerating my reaction to make him laugh,” says his father, Jean-Sébastien. “He likes to have fun, just like his mother and me.”

Eugénie, age 2, is as stubborn as both her mother, Valérie, and her grandfather. “When she wants something, she stops at nothing to try to get it,” Valérie says. Are these family traits, or learned behaviour? Probably a bit of both!

Environmental influences

The environment children grow up in plays an important role in the development of their character and personality. Identical twins are a good example of this. They are born with similar temperaments, since they share the same genetic makeup. Most of the time, they are also raised together. You may think that means they’ll have the same character. Think again! Each twin will have their own distinct character. This is due to their different life experiences. “Parents may not always realize it, but they act differently with each of their children,” Dionne explains.

What’s more, twins don’t always have the same friends or the same teachers. They also may not do the same activities. In short, they experience different things. “It’s this variety of experiences that gradually leads them to develop their own personalities,” Dionne adds.

And it’s not only a child’s family and immediate environment that shape their character and personality. Society also plays a part. For example, gender stereotypes encourage girls and boys to behave according to the characteristics associated with their gender. There is also evidence that stereotypes influence parents’ attitudes toward their children. In fact, everything your child sees, hears, and experiences influences how their personality develops.

Personality continues to develop right up to early adulthood.

This means you should avoid attributing negative traits to your child, even when it’s hard to keep your cool. For example, avoid saying things like “You’re being a pain,” “You’re a liar,” or “You’re too stubborn.” Labelling them in this way will just box them into a specific role. “The more that a child is told that they’re this or that, the more they’ll end up believing it,” Catherine Ruth Solomon Scherzer says. “In other words, if you tell them they’re a nuisance, they’ll be a nuisance.”

Nature or nurture?

Apart from temperament, what other characteristics will your child inherit? Science has yet to unlock all the secrets of genetics. But here are a few answers.

Apart from temperament, what other characteristics will your child inherit? Science has yet to unlock all the secrets of genetics. But here are a few answers.

Cognitive ability

This is one area that still remains a mystery! Intelligence is inherently difficult to define, and is therefore even more difficult to measure. This is why many specialists prefer to use the term giftedness instead of intelligence.

Both intelligence and giftedness are, in part, hereditary. A child’s environment (family, daycare, school, etc.) also plays an important role in the development of their cognitive ability. Your little one’s cognitive abilities are therefore a product of both their genes and their environment.

Height and weight

It’s often said that children will grow to be taller than their parents. While genetics play an important role in determining a person’s height, living conditions also contribute. Factors such as access to good nutrition and healthy lifestyle habits help support a child’s growth.

Over the last few centuries, thanks in particular to various advances in health and nutrition, our average height has increased from one generation to the next. Still, biology has its limits, and the average height of humans has recently evened out.

Genes also have an impact on a person’s weight. This is why members of the same family tend to become overweight or obese. According to Denis Richard, Université Laval’s Research Chair in Obesity, a person’s risk of becoming overweight is 2 to 8 times higher in families where obesity is present.

However, heredity is not the only factor. Behaviour and lifestyle habits can also increase or decrease risk. Furthermore, researchers are increasingly focusing on what happens during pregnancy. For example, studies have shown that if a pregnant woman has a metabolic disorder or an eating disorder, it could also have an impact on her baby.

An adopted child’s character

Children’s temperaments are largely defined by genetics. However, living environment and upbringing also help shape their temperament.

As a result, post-adoption experiences play an important role in how a child’s temperament and character develop. Chances are, the little one you’ve welcomed into your heart and home will end up being a lot like you in many ways!


You may be surprised to learn that genetics don’t always play a role in the conception of twins. There is no genetic factor associated with the probability of having identical twins, or babies from the same fertilized egg. It’s basically just a genetic lottery!

On the other hand, genetics do play a role with fraternal twins, or babies that develop from the fertilization of two separate eggs by two different sperm cells. This type of pregnancy occurs in women who release multiple eggs per cycle, which is a hereditary characteristic. That’s why women from families who have a history of fraternal twins are also more likely to have twins.

However, genetics is not the only reason for fraternal twins. Environment plays a role, too. For example, the probability of conceiving fraternal twins increases with the mother’s age, and is also more common in pregnancies conceived with the help of fertility treatments.

Who does your child take after?

They have Mom’s green eyes and Dad’s brown hair. A child’s physical appearance is mostly the result of their parents’ genetic makeup, but also partly a matter of chance.

They have Mom’s green eyes and Dad’s brown hair. A child’s physical appearance is mostly the result of their parents’ genetic makeup, but partly a matter of chance. Environment also plays a role.

Expecting? Wondering what colour eyes your baby will have? Statistically speaking, they’re most likely to be brown, as that’s the most common eye colour in the world. That said, genetics are what determines eye colour. It was long thought that eye colour was the result of a simple battle between dominant and recessive genes, with brown being more dominant than blue.

Every gene holds genetic information from both the father and mother. This information is contained in what are called alleles. Each gene has two alleles: one from the father and one from the mother.

In the past, if a child had blue eyes, it was thought that they had received two blue alleles from their parents (one from the father and one from the mother). Similarly, brown eyes were thought to result from one blue and one brown allele, or two brown alleles. However, recent discoveries have revealed that the truth is more complex.

Certain genetic traits, such as dark skin and brown eyes, can skip one or more generations.

In fact, eye colour is determined by dozens of genes, some of which have multiple variants. It’s the way these variants combine, and how genes interact, that determines eye colour.

That’s why there are so many different possible eye colours: hazel, chestnut brown, dark brown, grey, blue-grey, and so on. And though it’s rare, two blue-eyed parents can conceive a child with brown eyes. As a result, we can’t reliably predict an unborn child’s eye colour. It can change with just one gene variation!

Most physical characteristics are influenced by multiple genes. For example, if one parent has light skin and the other dark, their child’s skin colour can be any shade from light to dark. It’s the same with hair colour: there are an infinite number of possible shades. However, genes for dark hair (brown or black) are generally dominant over those for blond or red hair.

In addition to genes, environmental factors have an influence on certain physical characteristics. For example, nutrition can influence a child’s height.

Simply put, there’s no way of predicting what your baby will look like. But you can predict that your baby will be unique and, in your eyes, the most beautiful baby in the world!

Things to keep in mind
  • Genetics, family, environment, and society all have a hand in how personality develops.
  • You can help your child by adapting your behaviour and expectations to their temperament.
  • Physical characteristics are influenced by the interaction of several genes.
Naître et grandir

Source: Naître et grandir magazine, November 2015
Research and copywriting: Nathalie Vallerand
Scientific review: Élizabeth Harvey, Professor of Educational Studies at Université Sainte-Anne in Nova Scotia, and Bernard Angers, Professor of Biological Sciences at Université de Montréal
Updated: September 2023

Photos: Maxim Morin, Martine Lavoie, and iStock

Sources and references

Note: The links to other websites are not updated regularly, and some URLs may have changed since publication. If a link is no longer valid, please use search engines to find the relevant information.

  • Couillard, Kathleen. “Détecteur de rumeurs: Les enfants sont toujours plus grands que leurs parents? Faux.” Agence science presse. 2021. scientifique-en-chef.gouv.qc.ca
  • Failliot-Laloux, Marina. Mon enfant a du caractère! Le comprendre et savoir l’apaiser. Paris, Larousse, 2019, 80 pp.
  • INSIGHTS Intervention. insightsintervention.com
  • Kaniak-Urban, Christine, and Cornelia Nitsch. Élever son enfant selon sa personnalité. Paris, Éditions Vigot, 2012, 128 pp.
  • Encyclopedia on Early Childhood Development. child-encyclopedia.com
  • Neville, Helen, and Diane Clark Johnson. Temperament Tools: Working with Your Child’s Inborn Traits. Parenting Press, 2015, 126 pp.
  • Naître et grandir. Personnalité et tempérament. naitreetgrandir.com
  • Rothbart, Mary K. Becoming Who We Are. Temperament and Personality in Development. New York, Guilford Publications, 2012, 324 pp.
  • Simcoe, Mark, et al. “Genome-wide association study in almost 195,000 individuals identifies 50 previously unidentified genetic loci for eye color.” Science Advances, vol. 7, no. 11, 2021. science.org