Mr X was fooled by his wife, who used another man's semen to get in-vitro fertilization at a Barcelona clinic. carmen valiño

Six years after attending the birth of his son, and bringing him up as his own, a British man who shall be referred to as Mr X discovered that his ex-wife, Ms Y, had tricked him: the child was another man’s. It’s an old story, but with a new twist. The infidelity did not take place in a motel room, but inside a test tube.

The story dates back to 2004, when the wealthy couple visited the prestigious Instituto Marqués in Barcelona, a clinic specializing in in-vitro fertilization.

Just by asking people to identify themselves with their passport or identity card, these kinds of situations could be avoided”

Mr X provided sperm, which was frozen, and the couple signed a number of documents agreeing to the process by which the sample would be used to fertilize a donated egg for implantation into Ms Y’s uterus.

Four months later, Ms Y returned to the clinic with another man, her lover Mr P, who posed as Mr X and provided a new sperm sample. The clinic didn't bother to check his identity, and simply registered the new sample under Mr X's name. A few days later a fertilized egg was placed inside Ms Y’s uterus.

Nine months later, in the fall of 2005, she gave birth to a boy, whom we’ll call Z. To protect the child’s privacy, the courts have ordered that the identity of all parties concerned be kept anonymous.

While the court did not find the Barcelona clinic responsible, the case raises questions such as why it was so easy to replace Mr X’s sperm with that of Mr P.

“The law is very vague, and clinics all follow their own procedures,” says Esther Farnós, an adjunct professor of law at Barcelona’s Pompeu Fabra University and a specialist in assisted reproduction and false paternity claims. “Just by asking people to identify themselves with their passport or identity card, these kinds of situations could be avoided,” she says.

After talking to a number of clinics in Spain and the UK, it’s clear that there are no established procedures: “It can be embarrassing to ask people to identify themselves after you’ve seen them several times,” says one. “If people want to trick you they will,” says another. Some clinics take pictures of their clients, but sometimes people refuse to be photographed.

All the centers consulted by EL PAÍS say they accept semen samples brought in by wives or partners. Some clinics simply accept the husband’s signed and written approval, while others insist that he sign in person when the sperm sample is handed over.

“It’s very easy to forge a signature, so what are we supposed to do, use a handwriting expert?” asks Dr Marisa López-Teijón, head of assisted reproduction at Instituto Marqués.

In figures Around three percent of births are the result of assisted reproduction (16,000 in Spain).

In Spain, some 60,000 in-vitro inseminations are performed each year, around 10 percent of the European total.

The number of in-vitro treatments in Europe is increasing by seven percent a year.

Spain's 2006 assisted reproduction legislation is considered among the most advanced in the world, but it has not been sufficiently developed into lower-level provisions.

This doctor plays down the case of Mr X, listing all kinds of “unavoidable” fraud: wives who say they are single and get in-vitro fertilization, then tell their husbands that it happened naturally; husbands who use other men’s semen to get back at their wives; celebrities who turn up with people who are evidently not their partners; Muslim women inseminated by their sterile husbands’ brothers, as their religion mandates; and even what she calls "Boris Beckers"– women who try to have themselves inseminated with sperm they have collected through oral sex.

“Cheating between couples is something that has always happened, and always will,” says López-Teijón. “The only thing we’re concerned about is that we don’t make a mistake. Doctors are not police officers. What happened with Mr X wasn’t an error, there is no legal liability. We’re not here to prevent those kinds of things happening… and we don’t really care,” she concludes.

“Even if there is no liability, that was clearly a case of poor practice,” says Esther Farnós. “It’s true that some fraud cannot be avoided, but this one could have been. A sperm sample has consequences in terms of paternity, and it is astonishing that with something so important they never bothered to ask the man to identify himself. The problem is that there are no rules, there are not even any voluntary guidelines, but there are lobbies that have pressured hard to keep these legal loopholes open because it’s good for business.”

One legal consultant says that clinics have to walk a fine line between “behaving like the police” and “clarifying people’s marital status and identity”

But Fernando Abellán, a legal consultant with the Spanish Fertility Society, says that clinics have to walk a fine line between “behaving like the police” and “clarifying people’s marital status and identity”. He says there is a danger of over-bureaucratizing the process to deal with relatively few cases of fraud.

Despite denying any responsibility over what her clients do, Dr López Teijón says she has acted to prevent deception. A woman brought in a second sample of semen signed by her husband, because the first was not of sufficient quality. But when the sample was tested, it was clear that it was not from the same man. The clinic called the woman and told her that the sample had been accidentally dropped and that they needed a third sample. The woman never returned. In the case of Mr X, the clinic did not detect the swap because both samples had similar sperm counts.

Mr X’s suspicions were aroused when the clinic called him in 2005, precisely at the moment his wife was in Barcelona. “They seemed surprised to find me at home, so when my wife got back I asked her if she had been there with someone else.” She confessed, but said that she had later repented and used her husband’s semen sample, a tale that he believed.

Two years later, in 2007, when the couple had divorced, a girlfriend of Mr X suggested he contact the clinic to check that the first sperm sample had been used. The clinic erroneously said yes. “You’ve no idea the amount of irrelevant things we get asked,” says Dr López-Teijon. “The gentleman should have insisted that it was an important question.”

Perhaps they made a mistake, and their incompetence strengthened my belief that the child was mine, but they didn’t do it deliberately”

Ms Y told the court that her former husband knew she had gone to Barcelona with Mr P, and that she never deceived him. But the judge disagreed, ruling: “Mr X believed what his wife told him and the information provided by the clinic simply corroborated what he already believed. Mr X says he never contemplated legal action against the clinic: “It was my wife who tricked me. Perhaps they made a mistake, and their incompetence strengthened my belief that the child was mine, but they didn’t do it deliberately.”

Mr X gave his surname to Z, and after the separation, prior to discovering the truth, paid alimony and continued his parental role. He discovered he was not the father of Z in 2011 after the mother told him the truth when he began legal proceedings over visiting rights. He subsequently took a DNA test. The court ruling does not mention when the child became aware who his biological father was, but does state that Mr P had been a part of his life and is now registered as the official father.

Dr López-Teijón says that research shows that five to 10 percent of newborns are not the biological children of the men who believe themselves to be the fathers, and that this statistic is likely reflected in assisted reproduction.

In 2013, a British family court relieved Mr X of custody of the child, leaving the mother to decide on visiting rights. X then sued for damages, which a court accepted in March 2015, ordering Ms Y to pay him €54,000. The amount does not include the €19,500 paid in alimony during the six years following the divorce. “I hope that when he is 18 he will try to find me. This is a tragedy: they snatched a child from his father’s side and put somebody else in his place,” says X.