Sex is the underlying biological and genetic makeup that determine our physical characteristics. Gender is the psychological, social and cultural image that we display in relation to other humans. These meaning are rooted in culture because humans are not biologically programmed to behave in ways that signify one's assigned sex at birth These learned behaviors are taught from their surrounding cultures and environments. Different cultures have been shown to have different roles and types of behavior depending on one's sex and gender. For example, in the United States, many Americans view sex and gender as synonymous; those who are assigned Male at birth are expected to be masculine, and those who were assigned female ate birth are expected to be feminine. However, because of social progress of culture, this binary idea of sex is starting to become outdated, and the conceptual unwinding of sex, gender, and gender roles are starting to take hold.
Gender Display is how an individual conforms to the set of behaviors, roles, and codes that is expected, by social convention, of that particular gender. What is seen in the United States when traditional gender codes is challenged are usually social sanctions. Gender non comforting or transgender people are seen as outcasts. They are subject to discrimination, ridicule, vulnerable to hate crimes, and are excluded from many areas of society. Even now, as social exclusion grows stronger, formal sanctioning grows stronger as well, and we are now seeing many institutions, laws and legislations taking discriminatory actions against the trans community.
Gender identify is simply our identity. It is a part of who a person is, how they express themselves, what their role in society is and how they navigate the world around them. It allows people to connect with each other and develop relationships. Because of learned norms, people react differently to different genders, so how a person identifies will illicit from others certain behaviors and attitudes based on the gender they identify with. Being perceived the wrong gender you identify with is a cause for deep mental psychological discomfort; it robs you of your identity, your agency, and distorts your outwardly expression of your true being.
The Middle Sex people of India show us that there are cultures out there that do not ascribe to the cisgender normative view of gender that is pervasive in many societies, especially the West. In India, they are an accepted community that has their own role to play and are properly integrated into Indian society. India, Pakistan, Nepal, and Bangladesh have codified this "Third Gender" into existing law. In the United states, our binary view of sex and gender is simply a social construction that stems out of the Western European, Judeo-Chrisitan social values, and its subsequent view of the defined roles of a man and a woman. These beliefs are not set in stone or are any part of human nature. They were very intentionally implemented, through violence, indoctrination and subjugation.