The thing is, when you are promoting someone doing "grunt" work to a position where they will be supervising people and spending a lot more time communicating with you as your direct report, you kind of want that person to be on friendly terms with you. No one wants to argue over every little detail or god forbid a person who is strongly affected by their menstrual cycle (PMS and such). Someone who you can tell how far along their menstrual cycle they are just isn't good fit to a manager position in a high stress high performance environment.