Belgian authorities are looking into whether Simon, the newly discovered Dutch mass donor, also donated sperm in Belgium through fertility clinics or informal channels.

Simon, who also went by Daan, Saam, Jesse, Johan, and Maarten, is from the Groningen region and is believed to have fathered at least 120 children in the Netherlands. Dutch media now also suggests that he might have also donated sperm in the neighboring country.

The investigation is being conducted by the Belgian Federal Agency for Medicines and Health Products (FAMHP). Mass sperm donation, especially within the same country, raises the chances of children later unknowingly entering incestuous relationships.

Nieuwsuur, which was the first to report on Simon, also reported that he might have children in countries including Denmark and Germany. One of the mothers found other kids in Germany by using an online DNA database.

In the Netherlands, Simon reportedly spent around 15 years actively donating sperm. He had also reportedly lied to the future mothers about the number of kids he’s already fathered. He is believed to have mostly reached out to women directly through different online platforms.

The Donor Child Foundation told ANP it is in contact with a group of mothers in the Netherlands who have the donors’ children.

Simon was previously in contact with Nieuwsuur when they interviewed him for another story, not knowing that he was also a mass donor. When contacted recently about this case, he declined to comment. “I consciously choose to conduct any potential contact exclusively anonymously with the mothers themselves or through the official authority,” he said.