How a Fertility Doctor Impregnated Patients with His Own Sperm
Cover image of Kamil Baluk's book on Dr. Karbaat and his fertility clinic.


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How a Fertility Doctor Impregnated Patients with His Own Sperm

A Netherlands doctor secretly fathered at least 19 donor-conceived children in his own fertility clinic.

Different versions of this article originally appeared on VICE Poland and VICE Netherlands

In the 1980s and 90s, Dr Jan Karbaat ran one of the biggest fertility clinics in the Netherlands. Over the last few years, it's become increasingly clear that the place was a shambles. In the clinic – the Bijdorp Medical Centre in Barendrecht, near Rotterdam – semen from different donors was mixed together, women were lied to about whose semen their child had been conceived with and record-keeping was an absolute mess. The clinic was shut down in 2009, but more recently the story became even more grim – it turns out that Dr Karbaat, who died in April at the age of 89, secretly impregnated his clients with his own sperm.


Shortly after his death, a group of about 20 people who suspected their babies were conceived with Dr Karbaat's sperm filed a lawsuit, demanding a DNA sample from Karbaat. They had been building the case for a while, but Karbaat died before they could file it. Dr Karbaat had always refused to give DNA, but after his death – and after the lawsuit had been filed – his son donated his own DNA sample to Fiom, a Dutch organisation that helps people trace their parentage. Fiom found matches between the son and 19 donor-conceived children whose DNA they had in their database. Those 19 now know they were fathered by Dr Karbaat, but there are many other children conceived using sperm from the clinic who are still uncertain.

At the start of June, a court ruled that Dr Karbaat's DNA – extracted from personal belongings taken from his house after his death – can be used for further testing. As the BBC writes, "If the DNA profile matches, the children, most of them born in the 1980s, hope to sue the doctor, possibly on the grounds that they should not exist."

Polish writer Kamil Baluk spent three years investigating the malpractices of the Dutch sperm doctor and published a book on the subject earlier this year. He spoke to Dr Karbaat's former clients, the children who were conceived at his clinic and even to the doctor himself, before the DNA evidence came to light. I called Kamil Baluk to talk about his investigation into the dodgy doctor, and the recent developments in the case.


An unrelated pregnant belly. Image via | CC0

VICE: It's recently become clear that Dr Karbaat fathered at least 19 children with his clients. Were you surprised when you heard the news?
Kamil Baluk: No, I wasn't. When I was writing my book I knew he had likely used his own semen in his clinic, but I didn't have permission from my sources to state that openly. So I mentioned in the book that it was rumoured, but I left it open. I knew the names of a few people believed to be his biological children, but some didn't want to be interviewed while he was still alive.

You've spent three years investigating the clinic. What initially sparked your interest?
I first read a story about the clinic in a Belgian magazine, about a mother who was told by Dr Karbaat that her sperm donor had been white, but who gave birth to two children with darker skin. When I started investigating that further, I first spoke to Henrik Becker, a man whose mother had been to Karbaat's clinic too. His story was similar – according to documents provided by the clinic, his biological father was a white family man from the south of the Netherlands. But thanks to DNA testing, Fiom found out that wasn't true – his actual father was an unmarried biracial man. That's the same guy whose sperm had helped conceive the children in the Belgian article. Over time, the group of children who turned out to have been fathered by this man grew bigger and bigger. There are about 40 of them now.


What kind of guy is he?
I call him Louis, and he and his many children are a main focus in my book, which is titled Wszystkie dzieci Louisa, or "All of Louis' children". His sperm has been used more than 40 times, but Louis himself thinks he must have fathered at least 200 children, since he donated sperm every week for 17 years. He really wanted to meet his children – he explicitly asked Dr Karbaat about that, but the doctor had told him that was impossible.

Louis thinks he must have fathered at least 200 children, since he donated sperm every week for 17 years.

You met Dr Karbaat, didn't you?
Yes, I went by his house three times, and the third time his wife finally came to the door. I told her I'm a Polish writer and that I was writing a book about Dr Karbaat, his clinic and sperm donations. She let me in, and that's when I talked to Karbaat.

Was he a likeable guy? He's gotten away with so much.
I wouldn't say he was likeable, but he was definitely an interesting man. He was considered a successful guy in his time – he had been a renowned physician before he started his clinic, and he had been the medical director of the Zuider Hospital in Rotterdam. But he wasn't an empathic person at all, which especially for a doctor isn't right. When I talked to him about it, he just didn't seem to care that he'd used his own sperm in his clinic and had lied to his clients. It's gross, it's wrong, it's disrespectful. Same goes for the fact that the record-keeping in the clinic was a complete mess. He didn't care – he kept saying how proud he was of what he did, and when I said goodbye his wife kept repeating that he wasn't a bad person.


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Was he proud of what he'd done in his fertility clinic?
Absolutely. He told me that there are 6,000 people walking around in the Netherlands who wouldn't have existed without his clinic. He had wanted to help as many women get pregnant as possible, and only looked at the direct results. He said that seeing all these happily pregnant women had been the greatest satisfaction he had gotten out of his work.

Do you believe he did what he did because he wanted the best for his clients?
When I spoke to him at the time, I believed he did what he did because he thought that was the best for his clients. I believed that he had mixed sperm and used the same people's sperm so often because he didn't like rules and procedures surrounding sperm donation. Of course, I completely came back from that when I found out that he had used his own sperm to impregnate women. If you do that, you lose all credibility.

Dr Karbaat must have thought that his responsibilities ended when a woman became pregnant.

But still, there's a huge gap between "not liking rules and procedures" and "deliberately mixing sperm and lying to clients". Why did you believe at first he had the right intentions?
Well, if you look at the historical context, you'll find that around 50 or 60 years ago, many people believed that mixing sperm from different men would increase a woman's chances of getting pregnant. So I don't think he was the only doctor who did it. Dr Karbaat sold sperm as a product and wanted that product to be of the highest possible quality and have the highest success rate. I don't think he cared much about the donors, let alone about their future children. Dr Karbaat must have thought that his responsibilities ended when a woman became pregnant.

Do you think that focus on success, too, was a sign of the times?
Things were different in those days. In my book, I compare Dutch media reports from the past with what we know now, and with how donor-conceived children think about the way they were conceived. So much has changed. In the 70s and 80s, many people believed that it was a fundamental right for women to get pregnant. There were ads with slogans like, "Do a good deed, become a donor." That was also why donors always remained anonymous back then, to make it as easy as possible for men to donate their sperm.

How did that change?
When people started noticing how some children struggled with not ever being able to know who their father was, the focus shifted towards the needs of the child. Since 2004, Dutch sperm donors can't donate anonymously any more. Not that Dr Karbaat stuck to that rule, though – he still gave women anonymous sperm after 2004.

Man, he really didn't care much about rules and laws, did he?
No. But I think people generally cared less about rules and laws in the 70s and 80s. As someone from Poland, though, I was very surprised that the sperm donation system could be such a mess in a western country like the Netherlands.

This interview has been condensed and edited for clarity.