Dorothy Bishop is a world-leading expert in childhood language disorders.

Since the 1970s, she has been instrumental in bringing to light a little-known language disorder that may affect around two children per class starting primary school.

'Specific Language Impairment', or SLI, was originally deemed to be the fault of lazy parents who didn't talk to their children. But through her pioneering studies on twins, Dorothy found a genetic link behind this disorder, helping to overturn these widespread misconceptions.

Dorothy talks to Jim Al-Khalili about how families react when they discover there's a genetic basis to their problems, and why this language impairment isn't as well known as other conditions, like autism and dyslexia.

A critic of pseudoscience and media misreporting, Dorothy discusses her experiences of speaking out against folk psychology and bad science journalism.

Producer: Michelle Martin.