Interestingly enough, the way veined cheeses are made is that the curd is cut with the desired bacteria strain before the aging process is begun. AS the cheese ages, the mold spores grow inside the cheese. Obviously, the spores are harmless to people, but give the veined cheeses their charecteristic flavors.
The same is true for all cheeses. It is the particular bacterial agent added to the milk that gives the cheese much of its unique flavor. There are of course other factors, such as aging cheese in specific caves, aging in straw or hay, how long the aging process is continued, etc.
Of course, not being a cheese maker, I have to rely on the various articles I've read on the subject, and a little biological knowledge to boot.
Seeeeeeya; Goodweed of the North