nemo stated: I'm not a mother yet, but it struck me while reading your list that mother and father should both be eliminated, if your rule is applied. We have a non-gender specific alternative, parent.

Sorry, nemo, I'm not with you on this one. I agree that helen's hatter/milliner distinction is inconsistent with, indeed seems to cotradict, her aversion to the practice of distinguishing between people performing the same action simply on the basis of sex. However, mother and father are not the same function, so it seems to me that the diffference could be said to relate to job description rather than the sex of the practitioner.