It is not fully understood why survival and development is affected by cloning
Fragment of a discussion from Comments:Genetically modified dairy cows produce 'human milk'
http://en.wikipedia.org/wiki/Telomere#Lengthening_telomeres When you clone an animal, you take it's telomere length along with its DNA. The shortened telomeres provide a shorter life span. This can be observed in the case of Dolly, the cloned sheep. http://en.wikipedia.org/wiki/Dolly_(sheep)#Death' Where is your god now?