In June 2000, US President Bill Clinton and UK Prime Minister Tony Blair jointly proclaimed the completion of perhaps the most ambitious project in the history of biology: the reading of the 3bn DNA “letters” that make up the human genome. Stirring statements from the White House and 10 Downing Street, such as “Today’s announcement represents the starting point for a new era of genetic medicine,” punctuated the event.

And then ... nothing much happened for several years, at least as far as the public was concerned. Yes, scientists began to sequence genomes of other plant and animal species, from mice to chimpanzees, cress to corn, and they continued to find genes that caused rare inherited diseases like cystic fibrosis – but not the mainstream genes involved in common human diseases, such as diabetes.