Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Genes are known to play an important role in causing specific language impairment, but it is unclear how far a similar etiology is implicated in transient language delay in early childhood. Two-year-old children with vocabulary scores below the 10th centile were selected from a cohort of over 2,800 same-sex twin pairs whose language was assessed by parental report at 2, 3, and 4 years of age. These children with early language delay (ELD) were divided into cases of transient and persistent language difficulties on the basis of outcome at 3 and 4 years. A DeFries-Fulker analysis (J. C. DeFries & D. W. Fulker, 1985) was used to compute group heritability (h2g) of 2-year vocabulary delay separately for those with transient and persistent difficulties. When 3-year and 4-year language attainments were used to categorize outcomes, h2g was similar and modest (.25 or less) for both transient and persistent difficulties. However, when persistent difficulties were defined according to whether parents expressed concern about language at 3 years or according to whether a professional had been consulted about language difficulties at 4 years, heritability was significantly higher. For 289 children with no professional involvement at 4 years, heritability of 2-year vocabulary delay was close to zero, whereas for 134 children with professional involvement, a significant h2g of .41 (SE = .127) was found. Early language delay appears largely environmental in origin for 2-year-olds whose parents do not go on to seek professional help.


Journal article


J Speech Lang Hear Res

Publication Date





561 - 575


Child, Preschool, Cohort Studies, Diagnosis, Differential, Environment, Female, Humans, Language Development Disorders, Longitudinal Studies, Male, Surveys and Questionnaires, Time Factors, Twins