Why are sperm donors having hundreds of children? |
Some men are having vast numbers of children through sperm donation. This week the BBC reported on a man whose sperm contained a genetic mutation that dramatically raises the risk of cancer for some of his offspring.
One of the most striking aspects of the investigation was that the man's sperm was sent to 14 countries and produced at least 197 children. The revelation was a rare insight into the scale of the sperm donor industry.
Sperm donation allows women to become mothers when it might not otherwise be possible - if their partner is infertile, they're in a same-sex relationship, or parenting solo.
Filling that need has become big business. It is estimated the market in Europe will be worth more than £2bn by 2033, with Denmark a major exporter of sperm.
So why are some sperm donors fathering so many children, what made Danish or so-called "Viking sperm" so popular, and does the industry need to be reined in?
If you're a man reading this, we are sorry to break it to you, but the quality of your sperm probably isn't good enough to become a donor - fewer than five in 100 volunteers actually make the grade.
First, you have to produce enough sperm in a sample - that's your sperm count - then pass checks on how well they swim - their motility - and on their shape or morphology.
Sperm is also checked to ensure it can survive being frozen and stored at a sperm bank.
You could be perfectly fertile, have six children, and still not be suitable.
Rules vary across the world, but in the UK you also have to be relatively young - aged 18-45; be free of infections like HIV and gonorrhoea, and not be a carrier of mutations that can cause genetic conditions like cystic fibrosis, spinal muscular atrophy and sickle cell disease.
Overall, it means the pool of people that finally become sperm donors is small. In the UK, half the sperm ends up being imported.
But biology means a small number of donors can........