"In theology, the common phrase creatio ex nihilo ("creation out of nothing"), contrasts with creatio ex materia (creation out of some pre-existent, eternal matter) and with creatio ex deo (creation out of the being of God)."
Ex nihilo - Wikipedia, the free encyclopedia
Why would the pre-existent, eternal matter have the same 12C/13C as our atmosphere? Would the ex materia raisin have the slight preference for 12C as if it had a history of photosynthesis?
http://www.plantphysiol.org/content/101/1/37.full.pdf
The reason that we are able to track the amount of carbon that fossil fuel use puts in the atmosphere is that photosynthesis makes plants/algae have a higher concentration of 12C than the atmosphere. Would raisins made ex materia have an increase in 12C as if they went through a history of photosynthesis?