A review of all the world's cloned animals suggests that every one of them is genetically and physically defective. Ian Wilmut, co-creator of Dolly the sheep, the first mammal to be cloned from an adult cell, published his findings this weekend.

The study coincides with claims by researchers trying to create the first cloned human. In Italy, Dr Severino Antinori has claimed that three women are pregnant with cloned babies; in America, Dr Panayiotis Zavos has said he will achieve such a pregnancy within two years.