Donor-conceived Australians are desperate to know their biological family, with many terrified at the prospect of unknowingly sleeping with a sibling.
Their fears are prompting calls for world-first legislation to enshrine the legal right to know not only your biological parents, but your siblings.
The concerns were among many shared on Friday at a public hearing as part of a NSW inquiry into fertility support and assisted reproductive treatment.
The inquiry was told about a situation in which two people in NSW married before discovering they shared a sperm donor and were genetically siblings.
Currently, each state has its own system for handling these fertility issues, including different limits on how many families a sperm donor can contribute to.
Genea Fertility chief executive Tim Yeoh called for a national donor registry and a uniform 10-family cap on contributors.
This would raise the current five-family limit in NSW and WA.
These changes are said to be "widely accepted" as the right path forward for the fertility industry.
However, limits and state registers have not always been in place.
Many donor-conceived people live with the uncomfortable reality they might have hundreds of siblings they do not know about.
Witness Sarah Dingle told the hearing her biological father donated to the Royal North Shore Hospital more than 200 times and might have donated at other hospitals.
Each donation can create five to 20 children.
“I don’t like the fact that my biological father was paid," Ms Dingle said.
"Because he was paid, he went back and back and back."
Mr Yeoh said donors were no longer paid, but could be reimbursed for travel and other expenses.
Donor Conceived Australia director Rebecca Godwin said she was horrified to discover a co-worker was her sibling.
She lives with the fear of her children becoming intimate with a biological relative.
Ms Godwin made several recommendations to the inquiry, including a strengthened and enforced national donation limit, that donor-conceived siblings are notified about any medical condition a donor has, and access to ongoing counselling support and genetic testing for donor-conceived children.
