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- Genes play a part in about half of why babies walk at different ages.
- Parts of the brain like the cerebellum and motor cortex are affected by genes. This changes when babies reach motor skills like walking.
- Studies with twins show that identical twins walk at ages that are more similar than fraternal twins.
- Where babies live and their family’s situation also change how they learn to move, even with the genes they have.
- Walking earlier is not proven to be linked to being smarter or better at sports later.
Walking is a big moment in a baby’s life. It shows they can move around and do things on their own. Parents often wonder why some babies start walking sooner than others. Are late walkers just going at their own speed? Or is something in their genes guiding them? Looking at how genes and walking connect shows how much genes and a child’s growth are tied together. It also shows how their surroundings work with their body as they take those first steps.
What Are Baby Motor Milestones?
Motor milestones are basic skills babies learn in their first years. They help babies get more control over their bodies. These include important steps like:
- Rolling over
- Sitting without support
- Crawling
- Pulling up to stand
- Walking independently
These skills are part of something called gross motor development. This is about using large muscle groups for actions like crawling, walking, jumping, and climbing. Each step is a physical achievement. But it also shows the brain is getting more mature.
According to the World Health Organization, most babies start walking on their own around 12 months old. But the normal time frame is wide, from 8.2 to 17.6 months. This wide range happens because a baby’s body, brain, and what they experience all work together in ways that are complicated but interesting.
Doctors use these steps to check on a baby’s growth. But they are not strict deadlines. Just like personalities and how people look, each child learns to move at their own pace.
The Genetics of Movement: It Can Be Passed Down
When we say something is “heritable,” it means it can be passed down through genes. For motor skills like walking, heritability is surprisingly important. Scientists guess that genes explain about 50% of the difference in when babies start walking. So, half of why babies walk at different ages might come from things like their surroundings or how their bodies are. But the other half might be in their genes.
Genes don’t set an exact date for when a baby will walk. Instead, they make a baby’s body more likely to be ready at a certain time. For example, a child might get genes that affect:
- How tight their muscles are, which can help or slow down standing
- How fast their brain signals travel
- How naturally ready they are to try physical things
This shows why babies in the same family might walk at different times, even if they grow up in similar homes. It just shows that each child’s genes affect how fast they reach these steps.
Key Study Insight: Twin Research Shows Gene Influence
Studying twins is a good way to figure out how much genes matter compared to surroundings. For example, a big study in 2024 by Hannigan and others looked at lots of twins. They studied how genes related to when babies started walking.
The results were clear: identical twins, who share almost all their genes, started walking at ages that were much more similar than fraternal twins, who share about half their genes. This difference helped researchers figure out that genes play a part in about 50% of when walking starts.
And this research looked at things like how the twins were raised and where they lived. This made the findings about genes even stronger. This shows that genes and how a child grows are really tied together. They aren’t separate things.
Brain Growth and Walking
Walking might look like just using legs, but it takes the whole brain and body working together. Different parts of the brain and nervous system help babies walk. And these parts are affected by genes. They all work together so babies can move.
1. Cerebellum
This is at the back of the brain. The cerebellum helps with balance and staying upright. It makes movements smoother so babies don’t fall over as much when they stand.
2. Motor Cortex
This is in the front part of the brain. The motor cortex tells muscles what to do. It’s needed to start the steps that make a baby walk.
3. Spinal Cord and Peripheral Nerves
Signals for movement go from the brain, down the spinal cord, and out through nerves to the leg muscles. These connections need a fatty coating called myelin. This helps signals travel fast and smoothly to the leg muscles.
4. Synaptic Pruning
As babies grow, their brains get rid of connections they don’t need and make the important ones stronger. This is called synaptic pruning. Good, strong brain circuits are important for doing complicated things like walking.
These parts of the body and brain grow on timelines set by genes. Scientists think that differences in genes affect how this pruning and coating happen. This then affects when a baby’s brain is ready to start walking.
Which Genes Are Involved?
Finding the exact genes that help babies move is something scientists are still learning about. But they have found some genes that look important. These genes affect things like:
Muscle Function
- ACTN3: It helps muscles work and tells them what type they should be.
- Scientists look at different forms of this gene when studying sports ability. But these gene forms might also affect how babies learn basic movements.
Brain Connections
- BDNF (Brain-Derived Neurotrophic Factor): It helps brain cells grow and work.
- BDNF affects how connections in the brain change. This is key for learning and coordinating movements.
Cerebellum Growth
- Some genes scientists haven’t named yet affect how the cerebellum grows. This part of the brain is very important for balance and controlling movement.
- Big studies looking at many genes (called GWAS) are looking into how these genes connect to how babies behave and move.
Scientists don’t think there’s just one “walking gene.” They think many genes work together, each having a small effect. These gene groups don’t work alone. They work with the child’s whole body and everything they experience.
Genes vs. Environment: Both Matter
Looking at genes and how children grow shows that biology is important. But it’s just as important to say that where a child grows up matters too.
A child who might be likely to walk early because of their genes might still walk later if they don’t have the right chances to practice, things to encourage them, or space to move. Think about this:
- Babies who go to daycare earlier might see other babies walking and want to do it too.
- Babies who spend a lot of time in strollers or walkers might walk later.
- When parents clap, hold hands while walking, or offer toys, it can make babies more likely to try moving.
But a baby whose genes might make them walk later could still start sooner if they are in places that encourage lots of movement. Walking doesn’t have a set date in genes. It’s when a baby’s body is ready, and then they learn to do it by trying things.
Culture, Family Situation, and Walking
Like many things about how a child grows, walking is changed not just by what’s inside a baby, but also what’s around them. What’s normal in different cultures affects how parents raise babies. This changes how babies learn to move:
- For example, in Kenya and Uganda, parents often bounce babies and help them stand. This helps babies get strong early.
- But in many Western countries, babies spend more time in things like baby seats. This can mean less time on the floor building muscles.
Also, how much money a family has clearly matters. Families who have safe places to live, good food, and good doctors give kids a much better chance of reaching these steps sooner and feeling good about it.
So the age babies start walking can be different in different groups of people. This isn’t usually because of genes, but because of where and how they live. Genes and chances to practice keep working together.
Does Walking Earlier = Smarter or Stronger?
Parents often ask this question at playgrounds or when they visit the doctor: “Is walking early a sign of being very smart or good at sports?” The simple answer, based on science, is No.
Studies that follow children for a long time consistently show that walking early doesn’t mean a child will be:
- IQ
- able to plan or focus well
- coordinated later
- good at managing their feelings
In one study from 2013 by Adolph & Robinson, researchers looked at lots of information about how kids grow. They found that walking early didn’t clearly give kids an advantage in school or sports later on.
So it’s fun when your baby starts walking early. But it doesn’t mean they’re better or will be smarter later. And babies who walk later aren’t “behind”. They are just following their own healthy timeline.
What Helps Support Healthy Walking Timelines?
You can’t change your child’s genes. But you can help them learn to move well and get ready to walk in many ways:
- Tummy Time Every Day: This helps make their shoulders, core, and legs strong.
- Encourage Reach and Movement: Put toys where they have to try to reach them.
- Let Them Be Barefoot: Being barefoot helps them balance better and feel things with their feet.
- Don’t keep them in things: Limit how much time they spend in carriers, walkers, or bouncers.
- Cheer them on: Clap when they try. Don’t push them too hard.
Remember, walking is not a race. The main thing is to give them chances to move on their own in places that are fun and safe.
A Way to Help Doctors Find Issues
It’s normal for babies to walk at different times. But walking much later than the normal range can sometimes be a sign of a health issue. Doctors check when babies start walking as part of watching how they move overall. If a baby walks late, the doctor might suggest tests for:
- Cerebral palsy
- Down syndrome
- Duchenne muscular dystrophy
- Spinal muscular atrophy
Most doctors say it’s a good idea to check things out if a child isn’t walking by 18 months. This is extra important if they are also late with other skills like sitting or crawling. Finding any issues early helps kids get support sooner.
Is There One Right Time to Walk—Or Does It Just Depend on Genes?
Books and apps might give exact times for when babies should do things. But the real timing is much more flexible. Think of the “normal” time for walking as a range of months, not just one date.
It’s considered normal and healthy for babies to walk any time between 9 and 18 months. A child who walks later might still learn other ways to move quickly later and do better than others. Also, babies who walk early might learn to talk or use their hands for small things more slowly. Growing up healthy doesn’t happen in a straight line. It’s more like building something with many different parts that fit together when they are ready.
New Research: How Genes, Brains, and What Babies Do Connect
Today, scientists studying kids’ growth look at more than just DNA. New tools like special brain scans (fMRI) and ways to see how genes are working are helping scientists learn how moving around early changes a baby’s brain.
New studies are looking at how walking helps the brain grow. It seems to make parts of the brain that help with certain things work more:
- Learning to talk
- Knowing about others
- Understanding space
Some scientists think that walking helps babies learn more about the world around them and about other people. They think this might even change how their brain gets wired for things like paying attention, remembering, and figuring things out.
As studies of genes and brains come together, we might one day be able to guess not just when a baby will walk, but how moving around early changes their whole mind.
What This Means for Parents and People Who Work with Kids
Knowing how genes affect when babies walk changes how we can help them. If you are a parent, a doctor, or someone who studies how kids grow, knowing this helps you understand more and be kinder about timing.
- Parents: Don’t panic if your child isn’t walking by their first birthday.
- People who work with kids: When you check on a child, think about both their genes and their surroundings.
- Teachers and others: Help kids learn at their own speed and be happy that different kids learn to move at different times.
Believing in a child’s own way of growing, while also helping them, sets them up well for a good life.
Walking: How a Child’s Body and What They Experience Work Together
Walking is more than just reaching a step. It’s a big part of a longer story. When your child stands up and takes those first shaky steps, it’s not just about moving. It shows how their genes, brain cells, muscles, feelings, surroundings, and time have all come together inside them.
Understanding genes and how kids grow helps us understand better how and when this happens. Encouragement, patience, and presence will always matter more than dates on a calendar. In the end, every path to walking is as unique as the child taking the first step.
Reference
- World Health Organization (2006). WHO Motor Development Study: Windows of achievement for six gross motor development milestones. Acta Paediatrica, 450, 86–95. https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1651-2227.2006.tb02379.x
