Women score lower on the Kohlberg stages of moral development. It's a point of controversy in psychology (just like race and IQ). Most women are around a stage 3 or 4; their ideas of morality are based on avoiding disapproval and accepting whatever rules they think will maintain the group's happiness. This is slightly more developed than infants but a far cry from fully developed morality of universal ethical principles. Make no mistake there are some bright women capable of universal ethical principles (Ayn Rand for example) but most women score lower than men. You're right this is likely because there has never been any evolutionary pressure on women to develop their morality, it has never been their role in society to make important decisions. Fast-tracking women into important political and economic roles is just as disastrous as giving such powers to teenagers.