"Even when couples share more equitably in the work at home, women do two-thirds of the daily jobs at home, like cooking and cleaning up--jobs that fix them into a rigid routine. Most women cook dinner and most men change the oil in the family car. But dinner needs to be prepared every evening around six o'clock, whereas the car oil needs to be changed every six months, any day around that time, any time that day.... Men thus have more control over when they make their contributions than women do."