When sperm crosses borders, national safeguards fall short

In recent years, sperm donation has produced family trees of unprecedented size, stretching across countries and, in some cases, continents. Stories of “mass donors” have captured public attention, most recently through the Netflix documentary series, The Man with 1,000 Kids. It focused on a Dutch donor whose sperm was used to conceive hundreds of children across the world, exposing loopholes in the industry’s regulations.

Such cases have raised concerns not only about the psychological impact on children who discover they have dozens of half-siblings but also highlighted the risk of consanguinity – the possibility of unknowingly forming relationships with close genetic relatives.

An international investigative journalism project published in December exposed another potentially devastating medical consequence. According to the 14 public broadcasters involved in the probe, one donor whose sperm was used to conceive at least 197 children across 14 European countries over 17 years unknowingly passed on a rare genetic mutation associated with a very high lifetime risk of cancer, a condition known as Li-Fraumeni syndrome. Affected children are likely to develop some form of cancer including leukaemia...