Lifeboat Foundation

But the new study, which tracked four sheep cloned from the same ewe as Dolly, found they had aged normally.

Some of the animals did show mild — and in one case moderate — signs of osteoarthritis. But the researchers say that it was not sufficiently severe that any of the animals required treatment.

Dolly the sheep’s “siblings” are generally healthy, a study has shown, providing hope that cloning can yield animals free from degenerative illness.

The first mammal to be cloned from an adult cell — Dolly — died at the relatively young age of 6.5 years, having suffered from osteoarthritis.

This raised concerns that cloned animals might age more quickly.