Why was Dolly not genetically identical to the surrogate mother that carried her?

Dolly was not genetically identical to the surrogate mother because she was not produced through traditional reproduction, which involves the combination of genetic material from two parents. Instead, Dolly was created using a technique called somatic cell nuclear transfer (SCNT).12

In this process, the nucleus of a somatic (body) cell—specifically a mammary gland cell—was taken from an adult Finn Dorset ewe and transferred into an enucleated egg cell (an egg with its own nucleus removed) derived from a Scottish Blackface ewe. The surrogate mother served only as the host for the developing embryo; she provided the environment for gestation but did not contribute her own nuclear DNA to the offspring. Consequently, Dolly’s nuclear genetic material was derived entirely from the adult Finn Dorset ewe that provided the donor nucleus, making her a clone of that donor rather than the surrogate.1324