The world's first genetically modified humans have been created, it was revealed last night. The disclosure that 30 healthy babies were born after a series of experiments in the United States provoked another furious debate about ethics.

So far, two of the babies have been tested and have been found to contain genes from three 'parents'. Fifteen of the children were born in the past three years as a result of one experimental programme at the Institute for Reproductive Medicine and Science of St Barnabas in New Jersey.

The babies were born to women who had problems conceiving. Extra genes from a female donor were inserted into their eggs before they were fertilised in an attempt to enable them to conceive.

Genetic fingerprint tests on two one-year- old children confirm that they have inherited DNA from three adults – two women and one man. The fact that the children have inherited the extra genes and incorporated them into their 'germline' means that they will, in turn, be able to pass them on to their own offspring.

Altering the human germline – in effect tinkering with the very make-up of our species – is a technique shunned by the vast majority of the world's scientists. Geneticists fear that one day this method could be used to create new races of humans with extra, desired characteristics such as strength or high intelligence.

Writing in the journal Human Reproduction, the researchers, led by fertility pioneer Professor Jacques Cohen, say that this 'is the first case of human germline genetic modification resulting in normal healthy children'.

Some experts severely criticised the experiments. Lord Winston, of the Hammersmith Hospital in West London, told the BBC yesterday: 'Regarding the treat-ment of the infertile, there is no evidence that this technique is worth doing . . . I am very surprised that it was even carried out at this stage. It would certainly not be allowed in Britain.'