A man from the Netherlands has been ordered by the courts to stop donating sperm after allegedly fathering over 550 children worldwide.

The 41-year-old, named Jonathan in press reports, has been donating his sperm to fertility clinics since 2007 according to BBC News. In 2017, when it was discovered he had fathered over 100 children, he was banned from donating to sperm clinics in the Netherlands. According to the findings of a recent civil case, however, he continued to donate to clinics abroad, to people he met via online advertisement, and to Dutch sperm banks that offer services internationally.

While Jonathan's lawyers said that their client was motivated by his want to help people conceive, the court stressed that his actions could plausibly have negative consequences for the families who received the sperm, who are now "confronted with the fact that the children in their family are part of a huge kinship network. with hundreds of half-siblings, which they did not choose".

Guidelines used in the Netherlands allow sperm donors to father a maximum of 25 children in 12 families, though it becomes harder to police when donors can offer their sperm internationally. According to judges in the civil case, brought by a foundation aiming to protect the rights of children born via a donor, Jonathan has produced between 550 and 600 children. The judge added that he had "deliberately misinformed prospective parents about the number of children he had already fathered in the past".

The man has now been banned from fathering any more children via sperm donation, with a potential €100,000 ($110,0000) fine per breach. 

A surprising number of cases like this have happened in the Netherlands in recent years. One prolific sperm donor known as "Louis" fathered over 200 children via sperm donations, specifically hoping that if he donated enough of his sperm, one of his children would track him down. 

“If I had 10 children this way, there would be a very slim chance of success,” he told The Guardian in 2018. “But what if I had 100… or even more?”

In 2019, DNA analysis found fertility doctor Jan Karbaat fathered at least 49 children via his work at a Rotterdam Clinic, secretly using his own sperm instead of donor sperm. It is believed that the total could be as high as 60, though he died in 2017 aged 89, making the case much more difficult to investigate.