Because we rely on others. Nothing is done in isolation. Einstein could not have come up with his ideas if not for the work of scientists that came before him. Therefore, his ideas are not simply the product of his genius.
It is not just passed on genetically. Creative works do not just happen in isolation. They are inspired by the works of others. That doesn't even take into account the people who are involved in the physical production of our work. Look at the section I wrote on Martin Scorsese and you'll see what I mean.
I didn't deny that creative works do not happen in isolation, or that they are not inspired by the works of others, but you're ignoring my conclusion that the end result is down to the unique, and therefore singular, perception and interpretation of the individual, since no two people will preceive or interpret in the same way. If, as I believe to be the case, that perception and interpretation are unique to every individual, then the end result of that which has inspired or stimulated a genius to carry a work of art or an invention to it's ultimate fulfilment or conclusion is also unique, and is therefore singular.
The point I was making is that her environment and her experiences led to her coming up with that idea. The chances of her coming up with that idea in a different environment, with different experiences, are tiny.
So you're basically agreeing with me, only you're looking at it from a different angle?