Sir Ian and his team fused the genetic information from an adult sheep cell nucleus with an egg cell to form an embryo that developed into a genetically identical copy of the original adult.

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The adult cell whose nucleus was transferred into the egg that became Dolly had a male imprinted genome that was inherited at birth and copied to every cell of the donor's body.

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Reproductive cloning, which created Dolly the sheep in 1997, involves transferring the nucleus of an adult cell into an egg, giving the resulting embryo a full set of genes without the normal sperm-meets-egg fertilisation step.

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