(Dolly and the Dollies are Finn Dorset sheep, which can live up to 12 years.) This story, unfortunately, is a sad one. Dolly became infected with a virus unique to sheep that caused tumors to grow ...

She was born in 1996 after scientists figured out how to remove the DNA from the egg cell of a Scottish Blackface sheep and basically replace it with the DNA of a mammary cell from a Finn Dorset ...