Why are sperm donors having hundreds of children?

Some men have a large number of children through sperm donation. This week the BBC reported on a man whose sperm contained a genetic mutation that significantly increases the risk of cancer for some of his descendants.

One of the most striking aspects of the investigation is that this man’s sperm was sent to 14 countries and gave birth to at least 197 children. The revelation is a rare insight into the scale of the sperm donor industry.

Sperm donation allows women to become mothers when this would not otherwise be possible: if their partner is sterile, if they are in a homosexual relationship or if they are single parents.

Meeting this need has become big business. The European market is estimated to be worth more than £2 billion by 2033, with Denmark a major sperm exporter.

So why do some sperm donors father so many children, which is what made Danish or so-called “Viking” sperm so popular, and should we reign in the industry?

If you’re a man reading this, we’re sorry to break it to you, but the quality of your sperm is probably not good enough to become a donor – fewer than five out of 100 volunteers actually succeed.

First, you need to produce enough sperm in a sample – this is your sperm count – then take checks on their ability to swim – their motility – and on their form or morphology.

The sperm is also checked to make sure it can survive freezing and storage in a sperm bank.

You could be perfectly fertile, have six children and still not be a good fit.

The rules vary around the world, but in the UK you also need to be relatively young – between 18 and 45; be free of infections like HIV and gonorrhea, and not carry mutations that can cause genetic diseases like cystic fibrosis, spinal muscular atrophy and sickle cell disease.

Overall, this means that the pool of people who end up becoming sperm donors is small. In the UK, half of sperm ends up being imported.

But biology means that a small number of donors can give birth to a large number of children. It only takes one sperm to fertilize an egg, but there are tens of millions of sperm in each ejaculation.

Men will come to the clinic once or twice a week while they donate, which can last for months at a time.

Sarah Norcross, director of the Progress Educational Trust charity which works on fertility and genomics, said the shortage of donor sperm made it “a precious commodity” and “sperm banks and fertility clinics are maximizing the use of available donors to meet demand”.

Among this small pool of donors, some men’s sperm are simply more popular than others.

Donors are not chosen at random. It’s a process similar to the wild reality of dating apps, where some men get many more matches than others.

Depending on the sperm bank, you can browse photos, listen to their voices, find out what job they do: engineer or artist? – and check their height, weight and more.

“You know, if their name is Sven and they have blonde hair and they’re 6ft 1in tall and they’re an athlete and they play the violin and they speak seven languages, you know that’s a lot more attractive than a donor who looks like me,” says male fertility expert Professor Allan Pacey, pictured, who ran a sperm bank in Sheffield.

“Ultimately, people slide left and right when it comes to donor matching.”

Denmark is home to some of the largest sperm banks in the world and has gained a reputation for producing “Viking babies.”

Ole Schou, 71, founder of sperm bank Cryos International, where a single 0.5ml vial of sperm costs between €100 (£88) and more than €1,000 (£880), says the culture around sperm donation in Denmark is very different from that in other countries.

“The population is like a big family,” he says, “there are fewer taboos on these issues, and we are an altruistic population, many sperm donors also give blood.”

And this, according to Schou, has allowed the country to become “one of the few exporters of sperm”.

But he says Danish sperm is also popular because of genetics. He told the BBC that the “Danish blue-eyed, blond-haired genes” are recessive traits, meaning they must come from both parents to appear in a child.

As a result, the mother’s traits, such as dark hair, “could be dominant in the resulting child,” says Schou.

He says the demand for donor sperm comes mainly from “single, highly educated women in their 30s who focused on their careers and gave up family planning too late.” They now represent 60% of requests.

One aspect of the sperm donor investigation published earlier this week concerned how a man’s sperm was collected at the European Sperm Bank in Denmark and then sent to 67 fertility clinics in 14 countries.

Nations have their own rules about how many times a man’s sperm can be used. Sometimes it is linked to a total number of children, others limit it to a certain number of mothers (each family can thus have as many related children as it wishes).

The initial argument around these limits was to prevent half-siblings – who didn’t know they were related – from meeting, forming relationships and having children.

But nothing prevents sperm from the same donor from being used in Italy and Spain, then in the Netherlands and Belgium, provided that the rules are respected in each country.

This creates circumstances in which a sperm donor can legally father a large number of children. Although man is often in ignorance of this fact.

“Many recipients, as well as donors, are unaware that sperm from a single donor can be used legally in many different countries. This fact should be better explained,” says Sarah Norcross, who believes it would be “reasonable” to reduce the number of children a donor can have.

In response to the investigation into the sperm donor who passed on a gene that led to cancer in some of the 197 children he fathered, Belgian officials have asked the European Commission to establish a Europe-wide sperm donor registry to monitor sperm traveling across borders.

Deputy Prime Minister Frank Vandenbroucke said the industry was like the “Wild West” and “the original mission of offering people the opportunity to start a family has given way to a real fertility business.”

The European Society of Human Reproduction and Embryology has also proposed a limit of 50 families per donor across the EU. This system would still allow one donor’s sperm to produce more than 100 children if families each wanted two or more babies.

Concerns have been raised about the impact on children conceived through sperm donation. Some will be happy, others may be deeply distressed by the dual discovery of being made with donor sperm and being one of hundreds of half-siblings.

The same goes for donors, who are often unaware that their sperm is so widely distributed.

These risks are amplified by easily accessible DNA ancestry tests and social media where people can search for their children, siblings or the donor. In the UK, anonymity no longer exists for sperm donors and there is a formal process by which children learn the identity of their biological father.

Mr. Schou of Cryos says that more restrictions on sperm donation would only lead families to “turn to the private market, which is completely unregulated”.

Dr John Appleby, a medical ethicist at Lancaster University, said the implications of such wide use of sperm constituted a “vast” ethical minefield.

He said there are issues around identity, privacy, consent, dignity and more, making it a “balancing exercise” between competing needs.

Dr Appleby said the fertility industry had a “responsibility to control the number of times a donor is used”, but it would undeniably be “very difficult” to agree global regulation.

He added that a global sperm donor registry, which has been suggested, carried its own “ethical and legal challenges”.