I'm not quite sure if I understand the sarcasm or not.
Many women don't breast feed because they simply choose not to breast feed. Do you think these women are going to produce the same quantity of milk as women who are excited to breast feed and psychologically involved with the action? I think the answer should be readily apparent.
Like I said, its psychological as well as physiological. As the saying goes, "mind, body, and soul." Unfortunately, here in the West, we look at the mind and body in two different contexts rather than being one unit. If you were to go eastward in the world, into Asia, they would look the body as a whole. Entirely different approaches to medicine and thinking.