The era of personalised medicine, which would see drugs tailored to our genetic makeup, is at least 15 to 20 years away, according to a report by the Royal Society.

Using genetic tests, drug companies are increasingly able to identify which drugs will work best for different patients. With some drugs, a minor genetic change can make the difference between success or dangerous side effects.

But Sir David Weatherall, who chaired the society's working group, said too little was known about the genetic causes of disease for so-called pharmacogenetics to become common in the near future.