Last week, DNA tests confirmed what 49 adults have long suspected. Decades ago, when each of their mothers had sought treatment from Karbaat, the fertility doctor had impregnated them not with the sperm of their chosen donor, but with his own.

After years of demanding rights to the now-deceased doctor's DNA, the truth is finally out.

Joey Hoofdman, one of the people fathered by Karbaat, said his mother went to the clinic with the sperm of her partner, the man who raised Hoofdman as his son.

"We are all happy with the clarity and the information we now have so we can get on with our lives," said Hoofdman, according to the Associated Press.

"It is a wave of emotions. We are all happy we have met each other, but because there are so many, it is complicated," he added.

Hoodfman and his fellow accusers, who are seeking compensation, join a further 22 children recognised by Karbaat as his own. And there may be even more.

Some fear that Karbaat has fathered 200 children in his clinic, and while the doctor consistently denied these accusations when alive, there are reports that he personally boasted of at least 60 kids.

Since the new evidence was made public, the Dutch Donor Child Foundation says it's been contacted by three more people who hold similar suspicions of paternity fraud.

It's a tragic series of events, but it is not without precedent. Ever since we started using various medical techniques to assist human reproduction, this practice has also had a history of abuse and exploitation, usually by male physicians.

The first successful artificial insemination was performed by physician William Pancoast in 1884. Brought in for a routine fertility examination, his 31-year-old patient was knocked out with chloroform and inseminated - not with her husband's sperm, as she had been told - but with the sperm of one of the six medical students watching from the back of the room.

It remained a secret until the child was 25-years-old.

Even in the 1980s and 90s, when in-vitro fertilisation and sperm banks began to take off, there was little, if any, government regulation of these practices, not just in Europe but all over the world.

Many states in the US still do not have laws against this sort of behaviour. An infertility specialist convicted of artificially inseminating 52 patients with his own sperm in the 1990s, for instance, had to be charged with fraud and perjury in order to go to jail.

What's more, at one fertility clinic in the UK, a physician named Bertold Wiesner is accused of fathering more than 600 babies without telling the mothers.

Assisted reproduction has helped humanity to give birth to eight million babies since its inception, but the misuse of this medicine can be extremely harmful, especially when proper regulations and laws do not explicitly forbid certain behaviours.

Using this case as a wedge, a child rights group, called Defense for Children, is pushing for reform around anonymous donor laws in the Netherlands. The organisation hopes that one day, all children may seek out the anonymous donors that brought them into this world.

"The Karbaat case is the first enormous breakthrough," said an advisor to the group.