Nico Kuyt sits in the garden of his house in the Dutch seaside village of Katwijk aan Zee. He glances at his phone between sips of coffee as spots of rain blow past.One of the groups is called “The Kids”, with dozens of participants. Odd, because Kuyt decided never to marry or have a family.

He is one of 85 men in the Netherlands to find in recent years that sperm donations they made to private clinics were sold at home and abroad, leading to alarmingly high numbers of children from the same donors in violation of medical guidelines.It has shocked the nation as story after story has broken about clinics and in some cases individual doctors seemingly profiteering off donated sperm without the knowledge of the men who provided the samples.

Kuyt, a former IT worker who at 63 lives alone, discovered that he had 50 children: “One for every year of my productive life.”

The full extent of his situation was something he only uncovered slowly over the course of a decade. In 2004, he was invited in by the clinic to which he had first donated his sperm in 1998, the Kinderwens Medical Centre (MCK) fertility clinic in Leiderdorp, and told to his shock that he had about 30 children. Dutch guidelines had at the time outlined 25 as an upper limit.

There would be more surprises. When news of growing scandals around fertility doctor malpractice first appeared a decade ago, Kuyt was concerned that more may be out there and demanded answers from MCK. This time it told him he had 25 children in the Netherlands and 25 abroad.

“It is theft of something very intimate,” he said, reflecting on his profound disappointment with the clinic. “It is playing with life. That is absolutely forbidden. You must respect life at all costs.” 

When they reach 15 years old, the children can choose to contact him. Recently, he has found that each week can bring a new letter, a new video call, a new face from anywhere in the world.

“The last one I had was last week, an Italian, who is 19,” he said. “I write in Dutch and use Google Translate, because I’m not that good at Italian, and he sends back in Italian because his English isn’t the best. It is a bit of a tower of Babel for him.”

He said he made a short video, which he now uses to introduce himself to his children when they get in touch. Sometimes, he said, his past is not welcome. “In the video portrait I tell the history of my family [in the resistance], about the war with Germany, and I have the feeling that one of my German daughters found that so difficult that she didn’t want to have any more contact … But I am open and honest, because it is just the history of our family.”

Kuyt was in his late thirties between 1998 and 2000 when he decided to donate sperm to the fertility clinic. He had no idea that two decades later he would have fathered half a street. He knows, has called and has even met about 20 children from the Netherlands, Italy and Germany — he names Kiara, Carlotta, David, Raffaele, and has files of photos on his laptop.

A total of 4,684 Dutch donors like Kuyt gave sperm to help other families at a time when there were shortages and a growing demand from infertile couples. Although he did not want to marry or have a family, he donated about 50 times and also contributed for scientific research and embryo donation.

“Of course, I’m very Christian, and we don’t destroy lives,” he said. “So I donated it all. But it was all very quiet because the parents didn’t want it to be known and wanted to bring up children as their own … I didn’t hear anything, but they were very pleased with me, so I just did it.

“I don’t have any genetic problems. It has all gone well with the children, they really were wanted. And I am happy to have them.” 

He did not tell his brother and sister that he had so many children until after his parents died, but now there is no secret. He often video-called his children during the pandemic. “Look, it wasn’t the intention, and I do find it a bit much — it’s a lot of work,” he said. “And a lot more will come, of course, when they are old enough to find out.”

Since 1991, the UK has had a legal limit of ten families per sperm donor. The Netherlands, however, has since 1992 had only a medical guideline limit of 25.There was no law. From 2004, when anonymous donations were banned, Dutch clinics were supposed to hold to this maximum, which was lowered to 12 families in 2018. That figure became a legally enforceable maximum only in April this year.

But there have been growing concerns around the practices at some Dutch fertility clinics. First to come to light was the fertility doctor Jan Karbaat, from Barendrecht near Rotterdam: his clinic was shut by inspectors in 2009 and his family were taken to court in 2017, months after his death, by donor children who suspected they were related and wanted DNA testing. He himself was the donor, and is thought to have fathered as many as 200 children.

The names of other mass donors have emerged and in late April, after pressure from MPs, the Dutch government revealed almost one in 50 donors — 85 men in total — have more than 25 children. Six men have between 40 and 50 offspring.Five have up to 75. And one has between 100 and 125 children.

How could it have gone so wrong? Michiel Aten, 64, a former preacher and donor father to 21 children, started the Priamos support group for men who are victims of the misuse of their sperm donations. “Think about cattle, where there was a watertight system that functioned for 30 years and a farmer who didn’t register a calf got an immediate €100 fine,” he said.

“But they completely broke the rules … The desire for children is so great, people are prepared to pay a lot of money. And young men can be extremely fertile, as I was myself: I had a gift from nature and others could profit from it, so I gave it away and I hoped that other people could be happy.”

At a time of deregulation, he believes, too much trust was placed in individual companies. “The fact that a clinic went so recklessly over the boundaries — I can’t explain it any other way than that they wanted to make money,” he said.

In a country of just over 18 million people, the consequences can be dramatic. Ties van der Meer, chairman of the Stichting Donorkind foundation for donor-conceived children, knows of cases where half-brothers and sisters unknowingly had a physical sexual encounter. “This is not a pleasant thing to realise after you have just spent half a morning in bed,” he said.

“If you think about it, people with the same biological father will often have the same talents and interests, the same education potential, living in the same regional bubble of the same sports club, the same chess club, the same academic courses. You see that people meet each other. The risk is bigger than you think.” 

A spokeswoman for the Dutch health and youth care inspectorate confirmed it was investigating reports about the MCK clinic, including its working methods and whether donors gave informed consent.

A spokesman for the company that now owns the clinic, TFP Fertility, said: “We are aware of the historic situation involving sperm donor limits in the Netherlands and that there are some affected families and donors at the Kinderwens Medical Centre (MCK) which occurred prior to the clinic becoming part of TFP Fertility in 2019.While this happened prior to our ownership, we of course accept responsibility for actions of the previous owners and are currently liaising with those families and donors who may have been impacted, providing counsel and support to all where needed.”

Mark de Hek, a lawyer from Sap Letselschade Advocaten, who has been contacted by the donor fathers, wants a full-scale independent investigation into potential unlawful acts. “I have the impression that lawmakers totally failed to realise how important this is,” he said.

“You are creating new life, and that is a dramatic thing to do as a doctor. It has a huge impact on someone’s lives and the lives of their family. Every week you are at a birthday — it’s almost comic.”

The political pressure is growing for an independent inquiry and MPs including Wieke Paulusma, health spokeswoman for the socially liberal Democrats 66 party, also wants the men to receive an apology.

At the nearby beach, Kuyt looks out to sea like generations of other Dutchmen, not knowing what the tide might wash up on the shore. “It’s sunshine and rain,” he said. “But, of course, the rain brings life.”