You look at two sheep. They appear to be identical. You wonder if they are twins, but they're not. They have the same parents and look very similar, but their DNA is different.

Could two animals ever have exactly the same DNA? Not too long ago, most people would have said "No," but in 1996 some scientists in Scotland did it. They took the DNA from a cell in one sheep and used it to create a brand new sheep, genetically identical to the original. The baby sheep, named Dolly, made headlines around the world!