Genetic, neurological and cognitive determinants of success and failure in learning a first language.

Children who struggle to learn their first language for no obvious reason—such as hearing loss or intellectual disability—may have a condition called specific language impairment (SLI), and this research aims to pinpoint its causes across genetic, brain, and cognitive levels. The problem is that SLI is poorly understood at a fundamental level. Without knowing which aspects of language difficulty are inherited, how the brain's language areas develop in at-risk toddlers, or why some children fail to grasp meaning from word order, researchers cannot design targeted interventions or identify reliable biological markers. This project fills that gap by combining three approaches: a twin study to isolate heritable language traits, a longitudinal study tracking brain lateralisation in toddlers at risk, and a training study that probes exactly where verbal learning breaks down in school-aged children. If successful, this work could sharpen the diagnosis of SLI and distinguish it more clearly from other neurodevelopmental disorders. That would help clinicians, educators, and families understand a child's specific difficulties rather than applying a broad label. The research is primarily fundamental science—it seeks to explain a basic cognitive and biological puzzle rather than deliver an immediate treatment—but a deeper understanding of why language learning fails is a necessary step toward better support for affected children.