Twelve year old Sian Williams stutters, and has done for years.
"I would come home, I would cry my eyes out and pray to God to take away my, my voice completely. I hated the sound of, of, of my voice."
Over the years her mother Azelene has wondered about the exact cause of her daughter's speech disorder.
"I know she didn't experience any trauma. And it was interesting for me, you know, where does this start to come from? I did think at that point might be it might be down the family tree. And, but I was never sure.
A global study involving Australian experts is searching for the genes believed to cause stuttering.
Professor Angela Morgan from the Murdoch Children’s Research Institute says there is already evidence genetics plays a role.
"So at the moment, we know that 70 per cent of individuals who experience stuttering they do have a family history of stuttering. We also know that there have been four single genes identified to be associated with stuttering."
Boys are up to five times more likely to be affected by stuttering than girls.
"So stuttering actually occurs in 1 in 10 children who are of preschool age. But we know around 80 per cent of children actually recover, either with or without treatment. And the remainder can then go on to have a persistent stutter."
Chief study investigator - Professor Melanie Bahlo from The Walter and Eliza Hall Institute of Medical Research - says better understanding of what causes the speech disorder could lead to improved treatments.
"To get to better therapies, personalized treatment, you really need to know the genetic basis of this, of this disorder. Therefore we need to look for the genes."
Researchers want to recruit 3,000 Australians aged seven-years and over with a history of stuttering.
To take part in the study, volunteers need to complete an online survey, record a sample of their speech, and supply a saliva sample for DNA analysis.
So far almost 600 people have signed up.
The Australian Speak Easy Association supports people who stutter.
The president of its branch in Victoria, Sophie Hatcher, welcomes the study.
"I would like to see more people take part in it. Because if it can improve the quality of life of those who have a stutter I think it would have done a great service."
