Remember Dolly, the first mammal to be successfully cloned from an adult somatic cell? Her birth was announced in 1997. People tend to see clones as exact copies of the originals, but they are not. While their DNA is the same, as in monozygotic twins, variations in the environment can cause significant dissimilarities. Dolly lived to the age of six, giving birth "naturally" to a lamb named Bonnie, before being put down because of progressive lung disease and crippling arthritis. Since Dolly, many other large mammals have been cloned, including horses and bulls. Cloning is now considered a promising way of preserving endangered species.
From our Fake for Real series.