Somatic Cell Nuclear Transfer (SCNT), a process for replacing the nucleus of an egg cell with a nucleus containing genetic information of a different animal, seems to be very useful for cloning and species preservation.
It seems that SCNT where both nuclei come from the same species is much more effective/successful than interspecies (iSCNT) where each nuclei came from animals of different species. Why is that? Is it because there's different mitochondrial DNA? What other factors could potentially make iSCNT less viable than SCNT?