The results were released on 12 April, after a two-year legal battle. Dr Jan Karbaat never publicly admitted using his own sperm but claimed privately to have fathered around 60 children when he was director of the Medisch Centrum Bijdorp near Rotterdam. Most of the children were born in the 1980s and are now adults.
Joey Hoofdman said that knowing Dr Karbaat was his biological father allowed him to 'finally close the chapter'. 'After a search of 11 years I can continue my life. I am glad that I finally have clarity,' he said.
In 2017, several of Dr Karbaat's patients and their children began a court case to test their DNA against Dr Karbaat's, after suspicion grew that he had used his own sperm rather than that of the women's partners or anonymous donors to father the children (see BioNews 903).
The court agreed that there was evidence to suggest Dr Karbaat had done so, and permitted DNA tests to be performed on 27 of his personal objects. However, the court also stipulated that the results be sealed and that another judge would be required to rule whether the DNA results could be compared with the DNA of the children conceived at his clinic.
Following that ruling, Dr Karbaat's son voluntarily provided a sample of his own DNA for comparison, which established a genetic relationship to 19 children born following treatment at the clinic.
In February 2019, the Rotterdam District Court granted permission for the claimants to compare their DNA to that of Dr Karbaat (see BioNews 987). Overruling objections from Dr Karbaat's family, the judge said: 'If he did [use his own sperm], without announcing it at the time, his widow and other heirs cannot claim that the doctor's anonymity should be respected.'
Martijn van Halen, one of the children created using Dr Karbaat's sperm, speculated that Dr Karbaat was able to act with impunity because of the culture of silence that prevailed around gamete donation in the 1970s and 1980s, when doctors advised parents not to tell children. 'If something is kept secret from all sides, then the only person with all the information – and that is the doctor – has totally free rein,' he told the Associated Press.
Dr Karbaat died a month before the 2017 case aged 89. The clinic had closed in 2009 for failing to meet storage standards and paperwork irregularities.