Speaking on the eve of his presidential address to the annual meeting of the British Association for the Advancement of Science at Trinity College, Dublin, the former head of fertility medicine at the Hammersmith Hospital in London also criticised the "hype" over stem cells. He said stem cells are unlikely to be of much use for many years.
Lord Winston called on his colleagues to use more moderate language when describing scientific breakthroughs, singling out in his speech senior scientists and naming two Nobel laureates for making dangerously arrogant remarks.
"James Watson's assertion about the value of tampering with the human germ-line are a pretty good example," he said. Professor Watson, who won a Nobel prize for discovering the DNA double helix with Francis Crick, has extolled the possibility of altering the genes of germ-line sperm or egg cells to eradicate inherited diseases.
Lord Winston also criticised the Nobel laureate David Baltimore for claiming that the human genome offered the information needed to create a human being. "We knew what he meant, of course, but actually the sequencing brings us no nearer to the spectre of creating a human being whatsoever," he said.
He added that scientists risk a public backlash against their work if their claims were shown to be extravagantly misleading.
For instance, Michael Dexter, the former chief executive of the Wellcome Trust, said in 2001 that sequencing of the human genome was an invention more important than the wheel. He also compared it to the splitting of the atom. "Five years later, genetic medicine based on this work has had little impact on health care and it's unlikely to have much impact for some years."
Embryonic stem cells offer great potential benefits but many of the problems were glossed over when describing these benefits to the public, he said.
"Of course, the study of stem cells is one of the most exciting areas in biology but I think that it is unlikely that embryonic stem cells are likely to be useful in health care for a long time," he said.
Stem cells from embryos can produce abnormal numbers of chromosomes and there is a risk that rogue cells can cause random tumours in a patient. "All these difficulties and many others may be overcome in time. But during the political campaign to encourage the UK Parliament to accept liberal legislation, some parliamentarians were clearly led to believe that a major clinical application was just around the corner," Lord Winston said.
"As disappointment sets in ... we can expect a massive backlash by the right-to-life groups who are always ready to pounce when they perceive a chink in our arguments," he said.
Lord Winston also criticised the trend towards commercialisation of science, which he said increases secrecy and undermines its public role. "Once the pursuit of science becomes heavily geared to profit, which the public feels it is not sharing in any major way, scientists may be compromised. They may be perceived as ... not working merely for the public good," he told the conference.
Lord Winston's targets
Nobel Prize winner in physiology and medicine in 1962. Discovered the DNA double helix with Francis Crick.
Lord Winston said: "In recent years we have seen exaggerated claims made by leading scientists that are sometimes patently fatuous. James Watson's assertion about the value of tampering with the human germline are a pretty good example."
Nobel Prize in physiology and medicine, 1975. President of Caltech, won the prize for his work on virology.
On his claims that the human genome offered the information needed to create a human being, Lord Winston said: "We knew what he meant, but actually the sequencing brings us no nearer to the spectre of creating a human being whatsoever."