Here is how it works.
Way back in 1972, a fetus was aborted in the Netherlands. Inside that fetus were some itty bitty kidney cells. Those itty bitty kidneys cells have been cultured and descendant cells have been grown from them.
Whatever cells Senomyx used are who knows how many generations removed from the original cells. Senomyx is the actual company which created the flavor enhancers used by Pepsi.
Senomyx is not the only company which uses this line of cells. Many vaccines, drugs, and tasty foods have been developed through the use of these cells.
Anyway, Senomyx then forced the cells to take up tiny pieces of DNA from an adenovirus.
The result is new cells which are not human in any way, but which have a weird and serendipitous characteristic. They have receptors shaped identically to certain taste receptors you have in your mouth.
A receptor is like a keyhole. And the flavor molecule is like a key. The trick is to create a flavor molecule that fits in the receptor.
If the flavor enhancer fits in the artificially created receptor, then it will fit into the taste receptors in your mouth.
(cue Weird Science by Oingo Boingo)
So if you drink Pepsi with those flavor enhancers, you are not consuming the fetal cells. Nor are you consuming their descendants. Nor are you consuming bits of adenovirus. You are consuming flavor enhancers which fit perfectly in your mouth.
Mouth shaped flavor receptors.