"We know half of them won't have problems and will catch up with their peers. The other half will have problems and we would like to know how to identify those who won't catch up. From this study, we know that part of the reason is genetic and we would like to look for specific genetic markers of both temporary and more enduring delay in future research."
Dale said the researchers are following the twins in their study to find which children do and don't catch up. So far, they have found no relationship between delayed language acquisition and other abilities such as spatial and non-verbal skills.
The study, which was published in the journal "Nature Neuroscience," reaffirmed known gender differences in language delay: more boys than girls have this problem. Analysis of data indicated that parents are not treating boys and girls differently.
"Boys are more at risk for this, just as they are for just about everything else," he said.
Other members of the research team include Emily Simonoff, Thalia Eley, Bonny Oliver, Thomas Price and Shaun Purcell of the Institute of Psychiatry in London; Dorothy Bishop of MRC Cognition and Brain Science Unit in Cambridge, England; and Jim Stevenson of the Centre for Research into Psychological Development at the University of Southampton.