Sex and gender distinction
The distinction between sex and gender distinguishes sex, the biological makeup of an individual's reproductive anatomy or secondary sex characteristics, from gender, an individual's lifestyle (often culturally learned) or personal identification of one's own gender (gender identity). This distinction is not universal. In ordinary speech, sex and gender are often used interchangeably. Some dictionaries and academic disciplines give them different definitions and others do not.
Sex is annotated as different from gender in the Oxford English Dictionary where it says sex "tends now to refer to biological differences, while . . . [gender] often refers to cultural or social ones." The American Heritage Dictionary, however, lists sex as both "Either of the two divisions, designated female and male, by which most organisms are classified on the basis of their reproductive organs and functions" and "One's identity as either female or male," among other definitions. It also refers to a usage note associated with the gender entry.
A working definition in use by the World Health Organization (WHO) for its work is that "'[s]ex' refers to the biological and physiological characteristics that define men and women" and that "'[m]ale' and 'female' are sex categories".
In humans, biological sex is determined by five factors present at birth: the presence or absence of a Y chromosome, the type of gonads, the sex hormones, the internal reproductive anatomy (such as the uterus in females), and the external genitalia. People with mixed sex factors are intersexed. People whose internal psychological experience differs from their biological sex are transgender or transsexual.
Since the Renaissance until the 18th Century, there was prevailing an inclination among doctors towards the existence of only one biological sex. In some discourses, this view persisted into the eighteenth and nineteenth centuries. However, even at its peak, the one-sex model was a view among European people with high education. It is not known to have been a popular view nor one entirely agreed with by doctors who treated the general population. And, "[t]he ways in which sexual difference have been imagined in the past are largely unconstrained by what was actually known about this or that bit of anatomy, this or that physiological process, and derive instead from the rhetorical exigencies of the moment."
In the Oxford English Dictionary, gender is defined as, "[i]n mod. (esp. feminist) use, a euphemism for the sex of a human being, often intended to emphasize the social and cultural, as opposed to the biological, distinctions between the sexes.", with the earliest example cited being from 1963. It is defined in the American Heritage Dictionary (5th ed.) as both "Either of the two divisions, designated female and male, by which most organisms are classified on the basis of their reproductive organs and functions; sex." and "One's identity as female or male or as neither entirely female nor entirely male", with a Usage Note stating:
Some people maintain that the word sex should be reserved for reference to the biological aspects of being male or female or to sexual activity, and that the word gender should be used only to refer to sociocultural roles. Accordingly, one would say The effectiveness of the treatment appears to depend on the sex of the patient and In society, gender roles are clearly defined. In some situations this distinction avoids ambiguity, as in gender research, which is clear in a way that sex research is not. The distinction can be problematic, however. Linguistically, there isn't any real difference between gender bias and sex bias, and it may seem contrived to insist that sex is incorrect in this instance.
A working definition in use by the World Health Organization for its work is that "'[g]ender' refers to the socially constructed roles, behaviours, activities, and attributes that a given society considers appropriate for men and women" and that "'masculine' and 'feminine' are gender categories." However, the Food and Drug Administration uses gender instead of sex when referring to physiological differences between male and female organisms. Gender is now commonly used even to refer to the physiology of non-human animals, without any implication of social gender roles.
The Gay and Lesbian Alliance Against Defamation makes a distinction between sex and gender in their most recent Media Reference Guide. Sex is "the classification of people as male or female" at birth, based on bodily characteristics such as chromosomes, hormones, internal reproductive organs, and genitalia. Gender identity is "one's internal, personal sense of being a man or woman (or a boy or a girl).
Some feminist philosophers maintain that gender is totally undetermined by sex. See for example The Dialectic of Sex: The Case for Feminist Revolution, an important and widely influential feminist text.
The case of David Reimer who was, according to studies published by John Money, raised as a girl after a botched circumcision was described in the book, As Nature Made Him: The Boy Who Was Raised as a Girl. Reimer was in fact not comfortable as a girl and later changed sexual identity back to male when discovered the truth of his surgery. He eventually committed suicide.
Gender in the sense of social and behavioral distinctions, according to archaeological evidence, arose "at least by some 30,000 years ago". More evidence was found as of "26,000 years ago", at least at the archeological site Dolní Věstonice I and others, in what is now the Czech Republic. This is during the Upper Paleolithic time period.
Criticism of the sex vs. gender differences distinction
Evolutionary psychologist Michael E. Mills suggested in 2011 that the distinction between the terms "sex differences" vs "gender differences" is misleading and counter-productive. It implies that the behavior of an individual can be partitioned into separate biological and cultural factors—which is incorrect. (However, behavioral differences between individuals can be statistically partitioned, as studied by behavioral genetics). Instead, it would be more accurate to view behaviors of an individual as phenotypes—a complex interweaving of both nature and nurture. Given this, a more appropriate and useful distinction to make would be whether a behavioral difference between the sexes is due to a underlying trait that is either a sexually dimorphic (different) or sexually monomorphic (the same in both sexes) psychological adaptation.
Anne Fausto-Sterling, a biologist, historian, and gender studies professor, focus her point of view for sex and gender on nature versus nurture and the biological explanations versus the social explanations. Fausto-Sterling believed that sex is not always dimorphic which challenges what is said to be the norm. Biologically, sex describes the anatomy characteristics of the body while culturally, the masculinity and femininity comes into effect with psychological factors. With doctor’s perspective that intersex don’t belong, this complication links to cultural and social conceptions of the Intersexual Rights Movement, stating the infants will have to go through a measuring tool called the Phall-O-Metric, which measures phallus size to identify if the infant will have to go through surgery. Sex can also be identified biologically by the X and Y chromosomes. With unique pairs of X and Y chromosomes, the infant will have to go through surgery due to the social and cultural aspect of gender in the society to become the “standard” male or female.
Bonnie Spanier is a biologist who studied feminism. In Bonnie Spanier’s point of view, she compares how the media and science affect sex and gender. Spanier characterized sex determination as “abnormal, ambiguous, or intersexed.”  She describes how scientists make assumptions of sexual orientation and gender identity due to masculinity. Because scientists believe masculinity are more of the norm than the femininity, the society is shaped towards how the male functions. Since most scientists in the days are male, the facts about male and female are shaped around a bias factor. Facts in the scientific field are made and changed by the environment (nature versus nurture). According to Spanier, scientific observations make up what we see sex and gender as. In the article published in 1982, it states that “corpus callosum was larger in human females than males.”  Feminist perspectives on sex and gender are always different than the scientists that are male. Female and male are shaped differently in the society which gives us bias ideas in social and political perspectives. In the 1993 issue of the Time magazine, scientists come up with a different observation stating “biological determinism of sex differences in behavior and cognition reflect and reinforce prejudices about gender.”  In the field of science, sex is determined with biological factors while gender shapes what an infant becomes. Due to bias thoughts between masculinity and femininity, the society in sex and gender is shaped by behaviors of the humans.
Transgender and genderqueer
Transgender does not have one definition. Instead it is a group of "identities and experiences of sex and gender variance, changing, and blending."  This is when an individual's biological sex does not match up with which gender they identify themselves. Under the umbrella of transgender includes "transsexual people, cross-dressers, drag kings and queens, genderqueer people, gay men and lesbians who queer gender lines, the partners of trans people, and any number of other people who transgress binary sex." These individuals often undergo sex-reassignment surgery, take hormones, or change their style of life to feel more comfortable.
In July 2012 Gopi Shankar, a Gender activist and a student from The American College in Madurai wrote the first book on Gender-variants and coined the regional terms for genderqueer people in Tamil, Gopi said apart from male and female, there are more than 20 types of genders, such as transwoman, transmen, androgynous, pangender, trigender,, etc., and ancient India refers it as Trithiya prakirthi."
The sex/gender distinction also known as the Standard Model of Sex/Gender is disapproved and criticized by many feminists. This is due to its emphasis on sex being seen as a biological aspect, that is fixed, natural, unchanging, and consisting of a male/female dichotomy. It clearly fails to recognize anything outside the strictly and specifically enforced male/female dichotomy and creates a barrier between those that fit and those that are 'abnormal'. In order to prove that sex is not only limited to two categories Anne Fausto-Sterling's Sexing the Body uncovers the truth behind the birth of inter-sexual children. Hence the standard model (sex/gender distinction) is incorrect in its notion of there being only two sexes male and female because, “complete maleness and complete femaleness represent the extreme ends of a spectrum of possible body types”  In other words, there are multitudes of sexes in between the two extremes of male and female.
Therefore, rather than viewing sex as a biological construct, Feminists accept both sex and gender as a social construct. According to the Intersex Society of North America, “nature doesn’t decide where the category of ‘male’ ends and the category of ‘intersex’ begins, or where the category of ‘intersex’ ends and the category of ‘female’ begins. Humans decide. Humans (today, typically doctors) decide how small a penis has to be, or how unusual a combination of parts has to be, before it counts as intersex.”  Overall, sex is socially constructed because nature doesn't decide on who is seen as a male or female physically. Rather, doctors decide what seems to be a "natural" sex for the inhabitants of society. In addition gender, the behavior, actions, and appearance of females/males is also socially constructed because codes of femininity and masculinity are chosen and deemed fit by society for societal usage.
West and Zimmerman's "doing gender"
Used primarily in sociology and gender studies, the term "doing gender" refers to the concept of gender as a socially constructed performance which takes place during routine human interactions, rather than as a set of essentialized qualities based on one’s biological sex. The term first appeared in Candace West and Don Zimmerman’s article “Doing Gender”, published in the peer-reviewed journal, Gender and Society. Originally written in 1977 but not published until 1987, “Doing Gender” is the most cited article published in Gender and Society. West and Zimmerman stress that to understand gender as activity, it is important to differentiate between sex, sex category, and gender. Sex refers to the socially agreed upon specifications that establish one as male or female. Sex is most often based on an individual’s genitalia, or even their chromosomal typing before birth. West and Zimmerman consider sex categories to be dichotomous, and an actor is placed in a sex category by exhibiting qualities exclusive to one category or the other. During most interactions, others situate an actor’s sex by identifying their sex category however, West and Zimmerman stress that an actor’s sex need not align with their sex category. West and Zimmerman (1987) maintain that sex category is, “established and sustained by the socially required identificatory displays that proclaim one’s membership in one or the other category” (p. 127). Gender is the performance of attitudes and actions that are considered socially acceptable for one’s sex category. West and Zimmerman demonstrate that the interactional process of doing gender, combined with socially agreed upon gender expectations, holds individuals accountable for their gender performances. West and Zimmerman maintain that while doing gender appropriately strengthens and promotes social structures based on the gender dichotomy, doing gender inappropriately does not call into question these same social structures; only the individual actor is questioned. The concept of “doing gender” recognizes that gender both structures human interactions and is created through them.
However, some feminists go further and argue that neither sex nor gender are strictly binary concepts. Judith Lorber, for instance, has noted that many conventional indicators of sex are not sufficient to demarcate male from female. For example, not all women lactate, while some men do. Similarly, Suzanne Kessler, in a 1990 survey of medical specialists in pediatric intersexuality, found out that when a child was born with XY chromosomes but ambiguous genitalia, its sex was often determined according to the size of its penis. Thus, even if the sex/gender distinction holds, Lorber and Kessler suggest that the dichotomies of female/male and masculine/feminine are not themselves exhaustive. Lorber writes, "My perspective goes beyond accepted feminist views that gender is a cultural overlay that modifies physiological sex differences [...] I am arguing that bodies differ in many ways physiologically, but they are completely transformed by social practices to fit into the salient categories of a society, the most pervasive of which are 'female' and 'male' and 'women' and 'men.'"
Moreover, Lorber has alleged that there exists more diversity within the individual categories of sex and gender—female/male and feminine/masculine, respectively—than between them. Hence, her fundamental claim is that both sex and gender are social constructions, rather than natural kinds.
A comparable view has been advanced by Linda Zerilli, who writes, "[Monique] Wittig is critical of the sex/gender dichotomy in much feminist theory because such a dichotomy leaves unquestioned the belief that there is a 'core of nature which resists examination, a relationship excluded from the social in the analysis—a relationship whose characteristic is ineluctability in culture, as well as in nature, and which is the heterosexual relationship.' [¶] Putting sex in nature, gender in society, Wittig suggests, enabled feminists to interrogate the cultural construction of femininity; but this strategy also allowed dominant discourses to acknowledge the distinction without rethinking the foundations of their diverse theoretical enterprises and their concepts of subjectivity...."[a]
- Monique Wittig, feminist theorist and author of Les Guérillères, a lesbian feminist novel
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