For years, Arthur Kermalvezen, the child of a sperm donor, saw possible fathers everywhere he went. "I imagined it might be my teacher, the people I saw on the bus... and I was very angry because it's impossible to live like this."
When, as an adult, he fell in love with Audrey, another sperm donor baby from Paris, the question became even more pressing.
Audrey describes the moment they met at a gathering for donor conceived activists in 2010 as "love at first sight" - but was this connection a romantic or genetic attraction?
When they were born, there were only two sperm banks in Paris and many men had made multiple donations - so there was a real possibility they could be half-siblings.
Before building a life together, Arthur and Audrey needed to know whether they were related. But in France, laws governing genetic testing and donor anonymity made finding the answer extremely difficult.
In France, only a research scientist, doctor or judge can order and supervise a genetic test, and people can be fined more than €3,500 ($4,288; £3,191) for possessing a home testing kit. As a result, companies such as 23andMe, Ancestry and MyHeritage don't make their kits available in France.
Supporters of the law, in place since 1994, say it stops sensitive genetic data being given to commercial companies, and prevents family disputes being caused by unexpected results.
But Arthur points out that France is the only country in Europe that criminalises the use of such tests.
While searching for other donor-conceived people born before 1994, Audrey came across Arthur. He had written a book detailing his desire to learn more about his biological origins.
Audrey says she was struck by how precisely he expressed feelings she herself had struggled to articulate. Both had loving families, yet both found themselves drawn to questions about the unknown people who had helped to create them.
When they met in person the chemistry was immediate. So was the problem.
Before they could move from platonic friendship to a romantic relationship, and even build a life together, they had to know the truth about their fathers. But no one in authority was willing to tell them.
After months of searching, they found a doctor in southern France who, for €900 ($1,028; £764) in cash, conducted a genetic test which found that they were not related. But their unease remained as the doctor was breaking the law in sharing that result with them.
"We were worried he was a charlatan," Audrey says.
They considered using a home-testing kit to confirm the result, but as a lawyer, Audrey was determined to act within the law.
So, from 2010, she launched a series of legal challenges to the French system.
She wanted to know whether her donor was still alive and, if so, whether he still wished to remain anonymous. Could she access non-identifying information about how many times he had donated and whether Arthur could be among her half-siblings?
Her efforts failed.
After three years of legal challenges, the couple took a 'leap of faith' and got married.
In 2015, France's highest administrative court rejected Audrey's final appeal.
Shortly before the birth of their first child, a doctor agreed to investigate what information might exist about their respective donors. Under French law, a medical practitioner has access to this information about their patients, but is not allowed to share it with them.
The doctor found that their donors were born in different years - and so could not be the same man. A life-changing piece of information, but one they only gained because a doctor agreed to break the rules.
"It's completely weird," Audrey says, "because it means that the doctor can know more than me... about me."
Even with this new information, Arthur still worried they could be related, so after years of resisting it, they finally took a home DNA test.
Campaigners say the French ban has done little to stop people taking home tests, with the advocacy group DNA Pass estimating that well over a million French people have taken one. Many order them via friends in countries where they are legally obtainable - or by using forwarding services in neighbouring countries.
The test said they weren't related.
Many years later, a genetic match with an American led Audrey to her donor - a man called Philippe - but he had already died.
Audrey's mother wrote Philippe's family a letter, thanking them for his "gift" which she described as "immeasurable".
His family welcomed Audrey for a visit. "Everybody had tears in their eyes," recalls Audrey. Philippe's sister had never known he was a donor.
The discovery gave Audrey answers that she had sought for decades. She learned details about her biological family's medical history. She saw photographs and video footage of Philippe. "I can watch him, see how he moved and hear his voice."
Audrey's legal campaign and Arthur's book together helped drive changes to French donor-conception laws, allowing people conceived after April 2025 to access identifying information about their donors when they reach adulthood.
For now, however, France remains one of the few countries in Europe where at-home DNA testing is still prohibited.
Which means, for Audrey, the wider fight continues.
"Every person has the right to know their origins and the right to know their history," she says.
Based on an episode of The Gift on BBC Radio 4
