Jonathan Jacob Meijer is known as a serial sperm donor, and his DNA has been used to father 550 children in the Netherlands and other nearby countries.

But now, he’s facing a lawsuit – and a demand that he stop donating.

The Netherlands Donorkind Foundation is suing Meijer to stop him from donating, and accuse him of lying about the number of children he has fathered.

According to Dutch sperm clinic guidelines, a sperm donor should only father a maximum of 25 children or to 12 women, to prevent inbreeding or psychological problems for children born of donor sperm.

The case comes from a Dutch mother of one of Meijer’s children, who says she never would have chosen him if she knew he had already fathered over 100 children at the time.

“If you think about the consequences this could have for my child I am sick to my stomach,” she said.

Meijer is already on a donation blacklist but continues to donate abroad, including in Denmark and Ukraine. he approaches prospective parents online and through social media, and gives no indication that he plans to change his behavior. They’re hoping the lawsuit will force him to.