She was cloned by associates of the Roslin Institute in Scotland, using the process of nuclear transfer from a cell taken from a mammary gland.

"[1] Dolly was born on 5 July 1996 and had three mothers: one provided the egg, another the DNA, and a third carried the cloned embryo to term.

The hybrid cell is then stimulated to divide by an electric shock, and when it develops into a blastocyst it is implanted in a surrogate mother.

A commercial with Scottish scientists playing with sheep was aired on TV, and a special report in Time magazine featured Dolly.

[5] The next year, Dolly produced twin lambs Sally and Rosie; further, she gave birth to triplets Lucy, Darcy and Cotton in 2000.

A post-mortem examination showed she had a form of lung cancer called ovine pulmonary adenocarcinoma, also known as Jaagsiekte,[18] which is a fairly common disease of sheep and is caused by the retrovirus JSRV.

[22][23] The Roslin Institute stated that intensive health screening did not reveal any abnormalities in Dolly that could have come from advanced aging.

The first study to review the long-term health outcomes of cloning, the authors found no evidence of late-onset, non-communicable diseases other than some minor examples of osteoarthritis and concluded "We could find no evidence, therefore, of a detrimental long-term effect of cloning by SCNT on the health of aged offspring among our cohort.

[32] The reprogramming process that cells need to go through during cloning is not perfect and embryos produced by nuclear transfer often show abnormal development.

[35] Wilmut, who led the team that created Dolly, announced in 2007 that the nuclear transfer technique may never be sufficiently efficient for use in humans.

[37] In January 2009, scientists from the Centre of Food Technology and Research of Aragon in northern Spain announced the cloning of the Pyrenean ibex, a form of wild mountain goat, which was officially declared extinct in 2000.

[38][39] In July 2016, four identical clones of Dolly (Daisy, Debbie, Dianna, and Denise) were alive and healthy at nine years old.

[40][41] Scientific American concluded in 2016 that the main legacy of Dolly has not been cloning of animals but in advances into stem cell research.