In the late 1970s, donor insemination and IVF were taking off in Australia. It was the miracle that gave infertile couples a baby.
Those fortunate couples who received eggs or, more commonly, sperm from a donor were encouraged to go home, hope for a pregnancy and, for the sake of their family, never tell a soul.
The vast majority followed their doctor's instructions. They were the experts after all.
Now, 40 years later, many of these family secrets are being revealed, deliberately or accidentally. Sometimes it all spills out during a family argument or bitter divorce. Other times, people researching their ancestry uncover the truth through a DNA test kit bought over the internet.
An estimated 40,000 Australians have so far been conceived through a donor.
Many are seeking out donor relatives through formal applications to state registers or informal approaches via their parents' fertility clinic, social media and DNA testing companies.
People conceived in Victoria are covered by the world's only retrospective "donor linking" law.
Introduced in March 2017, the law allows adults conceived during the era of anonymity to access their donor's identity. Supported by counsellors at the Victorian Assisted Reproductive Treatment Authority, many of these donor-conceived adults and donors are meeting each other for the first time.
Some form close bonds and become involved in each other's families; others make contact simply to satisfy curiosity and gather medical information.
Many donors gave sperm more than once, and their offspring are now finding they also have donor siblings - people conceived using the same donor but raised by different parents.
Donor sibling groups can range from three to more than 30 siblings, which can be difficult - especially when some parents continue to withhold conception information.
A team of researchers from La Trobe University Law School and Swinburne University of Technology is exploring the experiences of donor-conceived adults, sperm and egg donors, and parents of donor-conceived children who have made contact with a donor relative.
If you are a donor, donor-conceived adult or parent of a donor-conceived child and have taken part in donor linking, please contact us in confidence at firstname.lastname@example.org or visit https://familiesofstrangers.com
Professor Fiona Kelly is director of the Centre for Health Law and Society at La Trobe University