Cloned animals appear to age normally, alleviating fears scientists had they were doomed to live short, unhealthy lives.
The world's first cloned mammal, Dolly the sheep, died aged six-and-a-half after suffering from osteoarthritis.
To see if this was a consequence of her conception - somatic-nuclear cell transfer (SCNT) - scientists in the UK looked at 13 cloned sheep aged between seven and nine, four of them genetically identical to Dolly.
They looked at their metabolisms, muscles, skeletons, joints and blood pressure, and found they were all relatively healthy, showing no signs of metabolic disease or high blood pressure. Only one had moderate osteoarthritis.
"From the current series of assessments we conclude that there are no long-term detrimental health effects of cloning by SCNT for a long-lived species such as the sheep," the study reads.
"This conclusion is consistent with less detailed longevity studies in cattle, and suggests that the ageing process in surviving clones of large animal species is not accelerated."
Previous research had found evidence cloned animals' DNA had shorter telomeres, which protect chromosomes from deterioration, suggesting this led to shorter lives. But shorter telomeres don't seem to be linked to premature aging in sheep, and don't seem to occur in cloned cattle at all.
"It follows that the relationship between telomere length, health and longevity in multicellular organisms is complex," and not necessarily directly correlated, the researchers conclude.
Dolly was born in 1996. She got her name from Dolly Parton, having been cloned from a mammary gland cell.
The findings were published in journal Nature Communications.