I work in a high tech chemical company where the staff is 50% male/female. However, the synthetic chemical 1/2 of the company is 90% male and the biochemistry 1/2 is 90% female. All hired by the same HR department. The ratio differences are simply due to sex of the applicants.  It would be ridiculous to have gender parity in each division. We hire the best people possible. If they can pee standing up or not has nothing to do with it.