A System Without Borders
Ties van der Meer is 47 years old and still cannot say with certainty how many biological siblings he has. Conceived through anonymous sperm donation at a private Dutch fertility clinic, his path to answers was blocked when the clinic’s doctor destroyed donor records after the Netherlands banned anonymous donation in 2004. He eventually located one sibling, who helped him piece together his biological father’s identity and connect with other genetic relatives – but the full picture remains incomplete. He chairs Stichting Donorkind, a Dutch foundation and advocacy group for donor-conceived people, and describes the situation plainly as “problematic.”
His case is not extreme by current standards. Some donor-conceived people who have searched for siblings have found tens, and in some cases hundreds. One woman who spent seven years tracing half-siblings found 25 of them, telling the Guardian: “It does make you feel a bit mass-produced.” That experience – multiplied across countries and decades – is now pushing European fertility specialists toward a formal, cross-border fix.
What ESHRE Is Proposing
At the European Society of Human Reproduction and Embryology (ESHRE) conference held in London on July 8, researchers and clinicians laid out plans to establish a Europe-wide limit on how many children a single sperm donor can father. The argument, put directly by Jackson Kirkman-Brown, a professor of reproductive biology at the University of Birmingham: “The only thing that really makes sense is a transnational limit.” Kirkman-Brown and his colleagues have spent months building toward this proposal.
The push comes against a backdrop of wildly inconsistent national rules. Malta and Cyprus sit at one extreme – both countries allow a donor to contribute to the birth of just one child. The UK permits donations to up to 10 families per donor. Denmark, another regulated market, sets its limit at 12 families. But these national caps are difficult to enforce because sperm does not stay within national borders. More than half of sperm donations used in the UK in 2020 were imported, with the majority sourced from Denmark or the United States. Denmark is one of the world’s largest sperm exporters, meaning its 12-family domestic ceiling has little practical effect on how widely a single donor’s genetic material spreads globally.
Today, many countries – including the UK – have banned anonymous egg and sperm donation outright. But anonymity has become increasingly impossible to maintain even where it remains technically legal. Genetic testing services from companies like Ancestry and 23andMe, combined with voluntary genetic registries, have given donor-conceived people tools to identify biological relatives across borders and generations. Because sperm can be frozen and stored for years before use, the current system also produces situations where a donor-conceived person traces a genetic parent only to discover that person died years earlier – or that they have biological siblings spread across multiple continents and age brackets.
When the Math Gets Dangerous
The case of Jonathan Meijer illustrates how badly the existing framework can fail. The Dutch man began donating sperm in 2007, and his donations were ultimately used to conceive between 550 and 600 children. Stichting Donorkind – the organization van der Meer chairs – took Meijer to court. In 2023, he was ordered to stop donating.
The implications go beyond emotional distress for those involved. With a donor reaching that scale of reproduction, the statistical probability increases that half-siblings living in different countries could unknowingly form romantic or sexual relationships. More immediately documented is the genetic risk. A sperm donor whose samples were distributed by a Danish sperm bank was later found to carry a genetic mutation significantly elevating the risk of multiple cancers. By the time the mutation was identified, his sperm had already been used to conceive at least 197 children across Europe. Some of those children developed cancer. Some died. Screening protocols exist, but this case confirms they are not a complete safeguard.
Why National Rules Cannot Solve a Transnational Problem
The structural flaw in current regulation is geographic. A donor in one country can contribute to clinics and sperm banks across multiple jurisdictions, each with its own counting system – or none at all. Denmark tracks families, not individual children. The UK does the same. But there is no shared database, no cross-border audit mechanism, and no agreed definition of what “limit reached” means when the sperm has already crossed three borders before being used.
The ESHRE proposal attempts to address this by starting with Europe and building toward a framework that could eventually carry international weight. Kirkman-Brown’s team has been working on the architecture of such a system for months, though the specifics of the proposed cap number were not finalized at the London meeting.
Genetic technology is also changing the timeline of these discoveries in ways that complicate everything. A donor-conceived person today might use a consumer DNA service not to find a living parent but to reconstruct a family tree around someone who has already died – receiving identifying information about a biological parent they have no chance of ever meeting. The same test might simultaneously reveal a half-sibling born years earlier or later, in another country, to parents who had no idea the same donor’s sperm was traveling that far.
Van der Meer knows one sibling. There may be others. That is not a personal failing or an administrative oversight – it is the direct output of a system that has, for decades, allowed sperm to move across borders faster than the rules designed to govern it.
