A 21-year-old woman from Gelderland is going to court in an effort to find out the identity of her sperm donor father, who is known to have had at least 57 children, the Volkskrant said on Wednesday. The man is known as K34 in hospital files.

The Rijnstate hospital where the insemination was carried out knows the man’s identity but has refused to provide it to his offspring, since new legislation was introduced in 2004. The paper says the case is the first of its kind in the Netherlands.

Earlier this year, judges did give permission to another group of donor children to test the DNA of the man they suspected of being their father, who had since died. Those test revealed Jan Karbaat, a fertility clinic owner, had used his own sperm to father at least 49 children.

The woman in the new court case, named as Maria, told the Volkskrant that finding out who her father was is becoming increasingly important to her. ‘Why would I not want to know who he is,’ she said. ‘He is part of my identity.

The paper says the woman’s mother had deliberately chosen a donor who was willing to be contacted by his offspring, but that by the time Maria first tried to contact him, he had withdrawn permission.

Maria knows from her father’s donor details he was a cattle farmer, had straight blonde hair and was already the father of three children.