Dublin woman Anna Corrigan said she does not believe that both of her baby brothers born in the Tuam Mother and Baby Home actually died there.
She believes her brother William may have been adopted illegally in the US as no death certificate was issued for him, she said.
A death certificate was issued for her oldest brother, John. Inspectors who visited the institution in the 1940s stated he was in an "emaciated" condition. Later, when his death was listed, a death certificate stated measles as a cause of death.
If the bodies of one or two of her brothers are identified with DNA tests, she wants the remains to be given to her for a family burial. "The Garda forensic team should have been sent to the site a long time ago. I want to give a sample of my DNA to help the investigation," she said.
When she was growing up, Ms Corrigan did not know her mother had two sons before she was married.
The boys were born in the Tuam institution and Ms Corrigan grew up believing she was an only child.
Her mother, Bridget Dolan, from Clonfert, Co Galway, was 81 when she died in 2001.
Ms Corrigan said her mother always believed that baby William was illegally adopted in the US.
She always hoped that William was alive and that he would track her down at her home in Dublin.
Ms Corrigan said an entry in a ledger at St Mary's Mother and Baby Home in Tuam stated William died on February 3, 1951.
But gardaí established that no death certificate was issued. The Dublin woman said she believed her mother was right in claiming her baby was brought to America and adopted illegally.
"I have made a missing person's report to gardaí," she said.
She has no evidence that William survived or was taken to the US, but a large number of babies were illegally adopted from mother and baby homes in Ireland and brought to the US in that period, she said.
A Garda spokesman told this newspaper: "The investigation in relation to William Joseph Dolan is being treated as a missing person enquiry."
I am the chairperson of the Tuam Babies Graveyard Committee.The committee was formed in August 2013. This group of like-minded people wished to do the right thing for the children who were buried in the grounds of what was once the St Mary's old orphanage.