Genes influence when babies start walking

The age at which babies take their first steps is strongly influenced by their genes, according to new research. Led by scientists in the UK and published in the journal Nature Human Behaviour, the study was made possible through an international collaboration with the Netherlands and Norway.

As noted by Professor Angelica Ronald, from the University of Surrey and Birkbeck, University of London, “Most babies take their first step sometime between ages of eight months and 24 months, so it is a wide window in which this exciting milestone happens.” For years, researchers knew that environmental factors could influence when babies begin to walk, but the new study shows that genetics also has a major impact.

Scientists analysed the genetic information of more than 70,000 infants and identified 11 genetic markers influencing when babies start walking. Their research found that genetics accounts for about a quarter of the differences in when children take their first steps, suggesting that, just like with other traits such as height, some children may naturally start walking earlier or later because of their genetic propensity.

“Until now, we didn’t understand what causes the wide differences between children in when they take their first step,” said study author Dr Anna Gui, a researcher at the University of Rome Tor Vergata and Birkbeck, University of London. “Parents might often worry that walking early or late is a bad sign or that they have done something wrong. We see that genetics play a considerable role in influencing the timing of this milestone.”

Walking isn’t just a key milestone in the development of a child; it is also connected in terms of genetic influences with many other important aspects of human development. The study found that the genetic factors influencing when children take their first step are partly the same genetic factors that influence brain development, including the amount of folding and ridges in the outer surface of the brain (the cortex). Moreover, walking later within the typical range was linked genetically with less chance of developing ADHD. Finally, the study showed that relatively later onset of walking was influenced by some of the same genes involved in higher educational attainment.

“We hope these new genetic findings can advance fundamental understanding about the causes of walking and be used to better support children with motor disorders and learning disabilities,” Ronald said.

“While parents should still see their GP if they are concerned, a slightly later start is not always a sign of problems. There is a lot of variety in when children take their first step on their own.”

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