Question: By being born, one is automatically assumed to be male or female although we are now seeing differences in this old assumption. What is the experience of one's own gender referred to as? 

Context paragraphs:
LGBT culture in Japan: Only recently has the Japanese language begun to distinguish sex and gender.  Additionally, no explicit connection had been made prior between gender and sexual preference.  The Japanese adopted the English term gender ("jendaa)" to describe cultural concepts of feminine and masculine.  Previously, "sei" was used to distinguish the binary biological sexes, female and male, as well as the concept of gender.  Many terms describing gender presentation had vastly irregular meanings such as "okama", whose definitions included: a gay male, a feminine-behaving male, or a crossdresser.  Umbrella terms such as these had a negative sociological impact, generalizing various queer identities into a single concept.  Similar to the experience of LGBTQIA persons in other countries, Japanese queers lacked the linguistic space to exist in.

Gender binary: The gender binary, also referred to as gender binarism (sometimes shortened to just binarism), is the classification of sex and gender into two distinct, opposite and disconnected forms of masculine and feminine.  Gender binary is one general type of a gender system.  Gender binary is one of the core principles of genderism; it describes a social boundary that discourages people from crossing or mixing gender roles, and from identifying with more than two forms of gender expression.  Sometimes in this binary model, "sex", "gender" and "sexuality" are assumed by default to align.  For example, when a male is born, gender binarism assumes the male will be masculine in appearance, character traits, and behavior, including having a heterosexual attraction to females.

Trigender: Trigenderism is a non-binary gender identity in which one shifts between or among the behaviors of three genders, which could include male, female, and third gender (or genderless, non-gender, polygender, or any other variety of genderqueer identities).  Someone who is also gender fluid may mix two or more genders at a time.  Trigender falls under the general category of genderqueer or androgyny, a gender identity that goes beyond the normal binary gender system (male and female) and tends to be a catch-all place for other gender identities.  It can also be seen as the equivalent cultures that recognize individuals to define their own sense of self.

Sex differences in medicine: Sex differences in medicine include sex-specific diseases or conditions which occur "only" in people of one sex (for example, prostate cancer in males or uterine cancer in females); sex-related diseases, which are diseases that are more common to one sex (for example, systemic lupus erythematosus occurs predominantly in females); and diseases which occur at similar rates in males and females but manifest differently according to sex (for example, peripheral artery disease).  Sex differences in medicine should not be confused with gender differences.  The Institute of Medicine recognizes sex differences as biological at the chromosomal level, whereas gender differences are based on self-representation and other factors including biology, environment and experience.  Sex differences in medicine should also not be confused with sexually transmitted diseases, which are diseases that have a significant probability of transmission through sexual contact.

Gender systems: Gender systems are systems of gender roles in societies.  A "gender role" is "everything that a person says and does to indicate to others or to the self the degree that one is either male, female, or androgynous.  This includes but is not limited to sexual and erotic arousal and response."  Gender identity is one's own personal experience with gender role and the persistence of one's individuality as male, female, or androgynous, especially in self-awareness and behavior.

Gender polarization: Gender polarization is a concept in sociology by American psychologist Sandra Bem which states that societies tend to define femininity and masculinity as polar opposite genders, such that male-acceptable behaviors and attitudes are not seen as appropriate for women, and vice versa.  The theory is an extension of the sex and gender distinction in sociology in which sex refers to the biological differences between men and women, while gender refers to the cultural differences between them, such that "gender" describes the "socially constructed roles, behaviours, activities, and attributes that a given society considers appropriate for men and women".  According to Bem, gender polarization begins when natural sex differences are exaggerated in culture; for example, women have less hair than men, and men have more muscles than women, but these physical differences are exaggerated culturally when women remove hair from their faces and legs and armpits, and when men engage in body building exercises to emphasize their muscle mass.  She explained that gender polarization goes further, when cultures construct "differences from scratch to make the sexes even more different from one another than they would otherwise be", perhaps by dictating specific hair styles for men and women, which are noticeably distinct, or separate clothing styles for men and women.  When genders become polarized, according to the theory, there is no overlap, no shared behaviors or attitudes between men and women; rather, they are distinctly opposite.  She argued that these distinctions become so "all-encompassing" that they "pervade virtually every aspect of human existence", not just hairstyles and clothing but how men and women express emotion and experience sexual desire.  She argued that male-female differences are "superimposed on so many aspects of the social world that a cultural connection is thereby forged between sex and virtually every other aspect of human experience".

Feminist bookstore: Feminist bookstores are retail bookstores that sell material relating to women's issues, gender, and sexuality.  These stores served as some of the earliest open spaces for feminist community building and organizing.

Other sex: "Gender" refers to social or cultural distinctions associated with being male or female.  Scholars generally regard gender as a social construct—meaning that it does not exist naturally, but is instead a concept that is created by cultural and societal norms. " Gender binary" is the system of viewing gender as consisting solely of two, opposite categories, termed “male and female”, in which no other possibilities for gender or anatomy are believed to exist.  This system is oppressive to anyone who defies their sex assigned at birth, but particularly those who are gender-variant or do not fit neatly into one of the two standard categories.  Gender identity, one’s internal sense of being male, female, neither of these, both, or other genders, is something that everyone has, and not everyone identifies their gender as male or female.

Gender identity: Gender identity is one's personal experience of one's own gender.  Gender identity can correlate with assigned sex at birth, or can differ from it completely.  All societies have a set of gender categories that can serve as the basis of the formation of a person's social identity in relation to other members of society.  In most societies, there is a basic division between gender attributes assigned to males and females, a gender binary to which most people adhere and which includes expectations of masculinity and femininity in all aspects of sex and gender: biological sex, gender identity, and gender expression.  In all societies, some individuals do not identify with some (or all) of the aspects of gender that are assigned to their biological sex; some of those individuals are transgender or genderqueer.  Some societies have third gender categories.

Sex differences in sensory systems: An organism is said to be sexually dimorphic when male and female conspecifics have anatomical differences in features such as body size, coloration, or ornamentation, but disregarding differences of reproductive organs.  Sexual dimorphism is usually a product of sexual selection, with female choice leading to elaborate male ornamentation (e.g., tails of male peacocks) and male-male competition leading to the development of competitive weaponry (e.g., antlers on male moose).  However, evolutionary selection also acts on the sensory systems that receivers use to perceive external stimuli.  If the benefits of perception to one sex or the other are different, sex differences in sensory systems can arise.  For example, female production of signals used to attract mates can put selective pressure on males to improve their ability to detect those signals.  As a result, only males of this species will evolve specialized mechanisms to aid in detection of the female signal.  This article uses examples of sex differences in the olfactory, visual, and auditory systems of various organisms to show how sex differences in sensory systems arise when it benefits one sex and not the other to have enhanced perception of certain external stimuli.  In each case, the form of the sex difference reflects the function it serves in terms of enhanced reproductive success.

Supporting paragraphs: Feminist bookstore Gender identity
Answer: Gender identity