A baby’s first step is not just an adorable moment—it is connected to numerous genes that influence brain development. Initially, witnessing a baby’s first step may seem like a simple occurrence. However, beneath that unsteady moment lies a complex interplay of biology, growth, and genetics. Through a comprehensive international study involving over 70,000 infants, scientists have gained insight into why some children begin walking earlier than others.
This groundbreaking research identified 11 regions in the human genome associated with the age at which a baby starts walking. Published in Nature Human Behaviour, the study revealed that approximately 24% of the variance in walking age is attributed to genetic differences—a proportion similar to the impact of genetics on traits such as intelligence or height.
The onset of walking (AOW) is frequently used by healthcare professionals as a milestone to monitor developmental progress. In many regions, a child not achieving independent walking by 18 months is considered a signal for further evaluation. While delayed walking can indicate issues like muscle disorders, neurological conditions, or developmental delays, only a fraction of late walkers eventually show signs of a developmental disorder.
Most babies begin walking between 8 and 18 months, but the timeline can vary significantly. Some infants may opt to shuffle on their bottoms instead of crawling, while others skip crawling altogether. Nevertheless, walking is a nearly universal milestone that signifies a crucial transition in both physical and cognitive development.
Research indicates that AOW is not solely determined by muscle strength or chance; instead, it reflects broader trends in brain maturation. Professor Angelica Ronald from the University of Surrey, a senior researcher in the study, highlights the significance of a child taking their first step, stating, “Most babies start walking between 8 and 24 months, marking a significant moment for both the child and parents.”
The team’s genome-wide association study (GWAS) focused on infants of European descent from four prominent cohorts. They identified over 11,900 genetic variants accounting for approximately 90% of the genetic influence on walking age, suggesting that the trait is highly polygenic. Among the newly identified genes, one located in the RBL2 region, active in the brain, was found to overlap with other crucial traits. For instance, children who walk later within the typical range tend to have a lower genetic predisposition to attention-deficit/hyperactivity disorder (ADHD) and are genetically associated with increased brain surface folding, a marker of complex brain development.
Dr. Anna Gui, affiliated with both the University of Rome Tor Vergata and Birkbeck, University of London, remarked, “Previously, the reasons for the considerable differences in the timing of a child’s first step were unclear.”
Parents may worry about their child’s walking milestone and its implications. Genetics significantly influence when a child starts walking. Using polygenic scores, researchers predicted walking age with 3% to 5.6% accuracy, suggesting genetic impact beyond shared environments. The timing of walking correlates with brain development, affecting educational attainment and behavior. Walking signifies a shift in independence and enhances learning and exploration. Children’s environment changes post-walking, accelerating language and cognitive skills. The study reassures parents that walking variations are normal, aiding early detection and intervention strategies. Genetic testing could complement developmental assessments, aiding early support identification. Environmental factors also influence walking time, highlighting the intricate role of genetics in child development. International collaborations and funding enhance such research.
Conducted by the Autism Research Initiative, this study moves us closer to understanding the progression of early childhood development and the role of genetics in a child’s journey from crawling to walking and beyond. This article was originally shared by The Brighter Side of News. Enjoy heartwarming stories like this? Sign up for The Brighter Side of News newsletter.
