For a decade Perth researchers have been following 1000 sets of twins from infancy, hanging on their every word.
But their interest in how and when toddlers learn to talk will evolve into the world's biggest and longest study of children's language and literary development, after they secured funding to follow the children through adolescence.
The Looking at Language study, which involves the University of WA-linked Telethon Institute for Child Health Research, Kansas University and the University of Nebraska Medical Centre, has been awarded five years funding by the prestigious US-based National Institutes of Health.
The Perth researchers hope the study will not only help children who struggle with language but will also reassure many parents of late-talkers that the development is normal.
They say while it is important to play and read with children to encourage them to talk, biological clocks also control language just like with learning to walk and this could not be accelerated.
UWA Professor Cate Taylor said the study's next stage would address fundamental questions about how and when children learn to talk, and how strugglers could be helped.
"We know most children start to talk between 12 and 24 months, yet we have no idea why some children begin much later," she said. "Language development can be very rapid and there is enormous variability so we need to get a handle on what is normal."
Already the study showed that in children aged two who were late-talkers, 80 per cent caught up by the age of seven.
The study aims to find early therapies for those in need.