A lot about our biology is intertwined with our culture. When such an association is encountered for the first time, it could sound interesting, intriguing even, but with time, it becomes an evident relationship because our culture plays an important role in our upbringing. For example, think about how the body’s olfactory wiring affects what we think about cow-dung.
Broadly speaking, scatological odors snub any inclination on the individual’s part to approach the source or even think about it for prolonged periods. Talking about excrement quells taste buds at the dinner table and there is an immediate response in the form of revulsion.
However, what could cause such a response is not a closed question. One answer that makes sense is that the brain interprets that excrement will be poisonous if consumed in any amount, and so turns the mind away from engaging with it in any fashion so as to minimize the risk of poisoning.
At the same time, in India, cow-dung is regularly used as fuel for cooking-fires and also for a multitude of ritualistic purposes. There is no revulsion of any sort amongst those who handle it, and if there had been any in the past, it could have been subdued.
If any test exists to exclude familiarity and false convictions, and establish that the excrement-poison relationship has been eliminated in the individual’s mind, this argument could be true.