I know people like to say gender and sex are different now days. I believe they are synonymous with eachother and that people too often confuse their personality traits with their gender identity. If we just didn't give so much creedence to it then your penis or vagina would mean absolutely nothing about who you are as a person besides your biological functions. People feeling as though they aren't a man or a woman and are somehow in between is a result of our inherent roles as men and women. If someone doesn't feel like they fit those roles, they might feel uncomfortable with calling themselves a man or woman. But really we just need to not give so much credit to our nature. We overcome our innate human nature all the time in order to operate as advanced beings.