Transgender people have a gender identity or gender expression that differs from their assigned sex.^[4][5][6] Some transgender people who desire medical assistance to transition from one sex to another identify as transsexual.^[7]*The%20Psychobiology%20of%20Transsexual]]trans umbrella term posite of their assigned sex (trans men and trans women), it may include people who are not exclusively masculine or feminine (people who are non-binary or genderqueer, including bigender, pangender, genderfluid, or agender).^[5][9][10] Other definitions of transgender also include people who belong to a third gender, or else conceptualize transgender people as a third gender.^[11]*The%20Transgender%20S]]transgender cross-dressers^[13]

Being transgender is independent of sexual orientation:^[14] transgender people may identify as heterosexual, homosexual, bisexual, asexual, or may decline to label their sexual orientation. The term transgender is also distinguished from intersex, a term that describes people born with physical sex characteristics "that do not fit typical binary notions of male or female bodies".^[15] The opposite of transgender is cisgender, which describes persons whose gender identity or expression matches their assigned sex.^[16]

The degree to which individuals feel genuine, authentic, and comfortable within their external appearance and accept their genuine identity has been called transgender congruence.^[17] Many transgender people experience gender dysphoria, and some seek medical treatments such as hormone replacement therapy, sex reassignment surgery, or psychotherapy.^[18] Not all transgender people desire these treatments, and some cannot undergo them for financial or medical reasons.^[18][19]

Many transgender people face discrimination in the workplace^[20] and in accessing public accommodations^[21] and healthcare.^[22] In many places they are not legally protected from discrimination.^[23]

Psychiatrist John F. Oliven of Columbia University coined the term transgender in his 1965 reference work Sexual Hygiene and Pathology, writing that the term which had previously been used, transsexualism, "is misleading; actually, 'transgenderism' is meant, because sexuality is not a major factor in primary transvestism."^[24][25] The term transgender was then popularized with varying definitions by various transgender, transsexual, and transvestite people, including Virginia Prince,^[7]*The%20Psychobiology%20of%20Transsexual]]ho used it in the December 1969 issue of, a national magazine for cross dressers she founded.^[26] By the mid-1970s both and in use as umbrella terms,^[1] and 'transgenderist' was used to describe people who wanted to live cross-gender without sex reassignment surgery (SRS).^[27] By 1976, transgenderist was abbreviated as TG in educational materials.^[28]

By 1984, the concept of a "transgender community" had developed, in which transgender was used as an umbrella term.^[29] In 1985, Richard Elkins established the "Trans-Gender Archive" at the University of Ulster.^[26] By 1992, the International Conference on Transgender Law and Employment Policy defined transgender as an expansive umbrella term including "transsexuals, transgenderists, cross dressers", and anyone transitioning.^[30] Leslie Feinberg's pamphlet, "Transgender Liberation: A Movement Whose Time has Come", circulated in 1992, identified transgender as a term to unify all forms of gender nonconformity; in this way transgender has become synonymous with queer.^[31]

Between the mid-1990s and the early 2000s, the primary terms used under the transgender umbrella were "female to male" (FtM) for men who transitioned from female to male, and "male to female" (MtF) for women who transitioned from male to female.

These terms have now been superseded by "trans man" and "trans woman", respectively, and the terms "trans-masculine" or "trans-feminine" are increasingly in use.^[32] This shift in preference from terms highlighting biological sex ("transsexual", "FtM") to terms highlighting gender identity and expression ("transgender", "trans woman") reflects a broader shift in the understanding of transgender people's sense of self and the increasing recognition of those who decline medical reassignment as part of the transgender community.^[32]

Health-practitioner manuals, professional journalistic style guides, and LGBT advocacy groups advise the adoption by others of the name and pronouns identified by the person in question, including present references to the transgender person's past.^[33][34] Many also note that transgender should be used as an adjective, not a noun (for example, "Max is transgender" or "Max is a transgender man", not "Max is a transgender"), and that transgender should be used, not transgendered.^[35][36][37]

In contrast, people whose sense of personal identity corresponds to the sex and gender assigned to them at birth – that is, those who are neither transgender nor non-binary or genderqueer – are called cisgender.^[38]

The term transsexual was introduced to English in 1949 by David Oliver Cauldwell^[2] and popularized by Harry Benjamin in 1966, around the same time transgender was coined and began to be popularized.^[7]The%20Psychobiology%20of%20Transsexual]]ince the 1990s, has generally been used to describe the subset of people^[39]%20%282006%2C%20ISBN%C2%A00-8166-4312-1%29%2C%20e]] sex reassignment surgery xample, transsexual men and women who can pay for medical treatments (or who have institutional coverage for their treatment) are likely to be concerned with medical privacy and establishing a durable legal status as their gender later in life.

Distinctions between the terms transgender and transsexual are commonly based on distinctions between gender (psychological, social) and sex (physical).^[41][42] Hence transsexuality may be said to deal more with physical aspects of one's sex, while transgender considerations deal more with one's psychological gender disposition or predisposition, as well as the related social expectations that may accompany a given gender role.^[43] Many transgender people reject the term transsexual.^[8]Understanding%20the%20transsexual%20]] ^[45]Christine Jorgensen transsexualtrans-gendert have to do with bed partners, it has to do with identity."^[46][47] This refers to the concern that transsexual implies something to do with sexuality, when it is actually about gender identity.^[48][3] Some transsexual people object to being included in the transgender umbrella.^{[49][50][51][52]} The definitions of both terms have historically been variable.

In his 2007 book Transgender, an Ethnography of a Category, anthropologist David Valentine asserts that transgender was coined and used by activists to include many people who do not necessarily identify with the term and states that people who do not identify with the term transgender should not be included in the transgender spectrum.^[49] Leslie Feinberg]]likewise asserts that some people) but a category imposed by observers to understand other people.^[50] However, these assertions are contested by the Transgender Health Program (THP) at Fenway Health in Boston. It notes that there are no universally-accepted definitions, and terminology confusion is common because terms that were popular at the turn of the 21st century may now be deemed offensive. The THP recommends that clinicians ask clients what terminology they prefer, and avoid the term transsexual unless they are sure that a client is comfortable with it.^[48]

Harry Benjamin invented a classification system for transsexuals and transvestites, called the Sex Orientation Scale (SOS), in which he assigned transsexuals and transvestites to one of six categories based on their reasons for cross-dressing and the relative urgency of their need (if any) for sex reassignment surgery.^[53] Benjamin considered a moderate intensity "true transsexual" to need either estrogen or testosterone as a "substitute for or preliminary to operation";^[53] people who meet Benjamin's definition of a "true transsexual" but do not desire SRS include Miriam Rivera. There are also people who have had SRS but do not meet the definition of "transsexual", such as Gregory Hemingway.^[54][55]

These comprise genderqueer/non-binary genders, cross-dressers/transvestites, drag kings and drag queens, and intersex persons.

Genderqueer or non-binary gender identities are not specifically male or female.

They can be agender, androgynous, bigender, pangender, or genderfluid,^[56] and exist outside of cisnormativity.^[57][58] Bigender and androgynous are overlapping categories; bigender individuals may identify as moving between male and female roles (genderfluid) or as being both male and female simultaneously (androgynous), and androgynes may similarly identify as beyond gender or genderless (postgender, agender), between genders (intergender), moving across genders (genderfluid), or simultaneously exhibiting multiple genders (pangender). Androgyne is also sometimes used as a medical synonym for an intersex person.^[59] Non-binary gender identities are independent of sexual orientation.

A transvestite is a person who cross-dresses, or dresses in clothes typically associated with the gender opposite the one they were assigned at birth.^[60][61] The term transvestite is used as a synonym for the term cross-dresser,^[62][63] although cross-dresser is generally considered the preferred term.^[63][64] The term cross-dresser is not exactly defined in the relevant literature. Michael A. Gilbert, professor at the Department of Philosophy, York University, Toronto, offers this definition: "[A cross-dresser] is a person who has an apparent gender identification with one sex, and who has and certainly has been birth-designated as belonging to [that] sex, but who wears the clothing of the opposite sex because it is that of the opposite sex."^[65] This definition excludes people "who wear opposite sex clothing for other reasons," such as "those female impersonators who look upon dressing as solely connected to their livelihood, actors undertaking roles, individual males and females enjoying a masquerade, and so on. These individuals are cross dressing but are not cross dressers."^[66] Cross-dressers may not identify with, want to be, or adopt the behaviors or practices of the opposite gender and generally do not want to change their bodies medically or surgically. The majority of cross-dressers identify as heterosexual.^[67]

The term transvestite and the associated outdated term transvestism are conceptually different from the term transvestic fetishism, as transvestic fetishist describes those who intermittently use clothing of the opposite gender for fetishistic purposes.^[68][69] In medical terms, transvestic fetishism is differentiated from cross-dressing by use of the separate codes 302.3^[69] in the Diagnostic and Statistical Manual of Mental Disorders (DSM) and F65.1^[68] in the ICD.

Drag is a term applied to clothing and makeup worn on special occasions for performing or entertaining, unlike those who are transgender or who cross-dress for other reasons. Drag performance includes overall presentation and behavior in addition to clothing and makeup. Drag can be theatrical, comedic, or grotesque. Drag queens have been considered caricatures of women by second-wave feminism. Drag artists have a long tradition in LGBT culture. Generally the term drag queen covers men doing female drag, drag king covers women doing male drag, and faux queen covers women doing female drag. Nevertheless, there are drag artists of all genders and sexualities who perform for various reasons. Some drag performers, transvestites, and people in the gay community have embraced the pornographically-derived term tranny to describe drag queens or people who engage in transvestism or cross-dressing; however, this term is widely considered offensive if applied to transgender people.^[70]

Intersex people have genitalia or other physical sex characteristics that do not conform to strict definitions of male or female, but intersex people are not necessarily transgender because they do not necessarily disagree with their assigned sex. Transgender and intersex issues often overlap, however, because they may both challenge rigid definitions of sex and gender.

The concepts of gender identity and transgender identity differ from that of sexual orientation.^[71] Sexual orientation describes an individual's enduring physical, romantic, emotional, or spiritual attraction to another person, while gender identity is one's personal sense of being a man or a woman.^[35] Transgender people have more or less the same variety of sexual orientations as cisgender people.^[72] In the past, the terms homosexual and heterosexual were incorrectly used to label transgender individuals' sexual orientation based on their birth sex.^[73] Professional literature often uses terms such as attracted to men (androphilic), attracted to women (gynephilic), attracted to both (bisexual), or attracted to neither (asexual) to describe a person's sexual orientation without reference to their gender identity.^[74] Therapists are coming to understand the necessity of using terms with respect to their clients' gender identities and preferences.^[73] For example, a person who is assigned male at birth, transitions to female, and is attracted to men would be identified as heterosexual.

Despite the distinction between sexual orientation and gender, throughout history the gay, lesbian, and bisexual subculture was often the only place where gender-variant people were socially accepted in the gender role they felt they belonged to; especially during the time when legal or medical transitioning was almost impossible. This acceptance has had a complex history. Like the wider world, the gay community in Western societies did not generally distinguish between sex and gender identity until the 1970s, and often perceived gender-variant people more as homosexuals who behaved in a gender-variant way than as gender-variant people in their own right. In addition, the role of the transgender community in the history of LGBT rights is often overlooked, as shown in Transforming History.^[76]

In 2015, the American National Center for Transgender Equality conducted a National Transgender Discrimination Survey. Of the 27,715 transgender and non-binary people who took the survey, 21% said the term "queer" best described their sexual orientation, 18% said "pansexual", 16% said "gay", "lesbian", or "same-gender-loving", 15% said "straight", 14% said "bisexual", and 10% said "asexual".^[77]

Most mental health professionals recommend therapy for internal conflicts about gender identity or discomfort in an assigned gender role, especially if one desires to transition. People who experience discord between their gender and the expectations of others or whose gender identity conflicts with their body may benefit by talking through their feelings in depth; however, research on gender identity with regard to psychology, and scientific understanding of the phenomenon and its related issues, is relatively new.^[78]True%20Selves%3A%20]]he terms, e transvestism,* gender identity disorder in adolescents or adults,* and gender identity disorder not otherwise specified are listed as such in the International Statistical Classification of Diseases (ICD) by the WHO or the American Diagnostic and Statistical Manual of Mental Disorders (DSM) under codes F64.0, F64.1, 302.85, and 302.6 respectively.^[79]

The validity of the diagnosis and its presence in the forthcoming ICD-11 is debated.

France removed gender identity disorder as a diagnosis by decree in 2010,^[80][81] but according to French trans rights organizations, beyond the impact of the announcement itself, nothing changed.^[82] In 2017, the Danish parliament abolished the F64 Gender identity disorders. The DSM-5 refers to the topic as gender dysphoria while reinforcing the idea that being transgender is not considered a mental illness.^[83]

Transgender people may meet the criteria for a diagnosis of gender identity disorder (GID) "only if [being transgender] causes distress or disability."^[71] This distress is referred to as gender dysphoria and may manifest as depression or inability to work and form healthy relationships with others. This diagnosis is often misinterpreted as implying that transgender people suffer from GID; this misinterpretation has greatly confused transgender people and those who seek to either criticize or affirm them. Transgender people who are comfortable with their gender and whose gender is not directly causing inner frustration or impairing their functioning do not suffer from GID. Moreover, GID is not necessarily permanent and is often resolved through therapy or transitioning. Feeling oppressed by the negative attitudes and behaviors of such others as legal entities does not indicate GID. GID does not imply an opinion of immorality; the psychological establishment holds that people with any kind of mental or emotional problem should not receive stigma. The solution for GID is whatever will alleviate suffering and restore functionality; this solution often, but not always, consists of undergoing a gender transition.^[78]

Clinical training lacks relevant information needed in order to adequately help transgender clients, which results in a large number of practitioners who are not prepared to sufficiently work with this population of individuals.^[85] Many mental healthcare providers know little about transgender issues.

Those who seek help from these professionals often educate the professional without receiving help.^[78] This solution usually is good for transsexual people but is not the solution for other transgender people, particularly non-binary people who lack an exclusively male or female identity. Instead, therapists can support their clients in whatever steps they choose to take to transition or can support their decision not to transition while also addressing their clients' sense of congruence between gender identity and appearance.^[17]

Acknowledgment of the lack of clinical training has increased; however, research on the specific problems faced by the transgender community in mental health has focused on diagnosis and clinicians' experiences instead of transgender clients' experiences.^[86] Therapy was not always sought by transgender people due to mental health needs.

Prior to the seventh version of the Standards of Care (SOC), an individual had to be diagnosed with gender identity disorder in order to proceed with hormone treatments or sexual reassignment surgery. The new version decreased the focus on diagnosis and instead emphasized the importance of flexibility in order to meet the diverse health care needs of transsexual, transgender, and all gender-nonconforming people.^[87]

The reasons for seeking mental health services vary according to the individual.

A transgender person seeking treatment does not necessarily mean their gender identity is problematic.

The emotional strain of dealing with stigma and experiencing transphobia pushes many transgender people to seek treatment to improve their quality of life, as one trans woman reflected: "Transgendered individuals are going to come to a therapist and most of their issues have nothing to do, specifically, with being transgendered. It has to do because they've had to hide, they've had to lie, and they've felt all of this guilt and shame, unfortunately usually for years!"^[86] Many transgender people also seek mental health treatment for depression and anxiety caused by the stigma attached to being transgender, and some transgender people have stressed the importance of acknowledging their gender identity with a therapist in order to discuss other quality-of-life issues.^[86] Others regret having undergone the procedure and wish to detransition.^[88]

Problems still remain surrounding misinformation about transgender issues that hurt transgender people's mental health experiences.

One trans man who was enrolled as a student in a psychology graduate program highlighted the main concerns with modern clinical training: "Most people probably are familiar with the term transgender, but maybe that's it.

I don’t think I've had any formal training just going through [clinical] programs... I don’t think most [therapists] know.

Most therapists—Master's degree, PhD level—they've had... one diversity class on GLBT issues.

One class out of the huge diversity training.

One class.

And it was probably mostly about gay lifestyle."^[86] Many health insurance policies do not cover treatment associated with gender transition, and numerous people are under- or uninsured, which raises concerns about the insufficient training most therapists receive prior to working with transgender clients, potentially increasing financial strain on clients without providing the treatment they need.^[86] Many clinicians who work with transgender clients only receive mediocre training on gender identity, but introductory training on interacting with transgender people has recently been made available to health care professionals to help remove barriers and increase the level of service for the transgender population.^[89]

The issues around psychological classifications and associated stigma (whether based in paraphilia or not) of cross-dressers, transsexual men and women (and lesbian and gay children, who may resemble trans children early in life) have become more complex since CAMH (Centre for Addiction and Mental Health) colleagues Kenneth Zucker and Ray Blanchard were announced to be serving on the DSM-V's Sexual and Gender Identity Disorders Work Group.^[90] CAMH aims to "cure" transgender people of their "disorder", especially in children. Within the trans community, this intention has mostly produced shock and outrage with attempts to organize other responses.^[91] In February 2010, France became the first country in the world to remove transgender identity from the list of mental diseases.^[92][93]

A 2011 study carried out by the Williams Institute (a UCLA think tank) found that 41% of transgender people had attempted suicide, with the rate being higher among people who experienced discrimination in access to housing or healthcare, harassment, physical or sexual assault, or rejection by family.^[94]

Autism is more common in people who are gender dysphoric.

It is not known whether there is a biological basis.

This may be due to the fact that people on the autism spectrum are less concerned with societal disapproval, and feel less fear or inhibition about coming out as trans than others.^[95]

Medical and surgical procedures exist for transsexual and some transgender people, though most categories of transgender people as described above are not known for seeking the following treatments.

Hormone replacement therapy for trans men induces beard growth and masculinizes skin, hair, voice, and fat distribution. Hormone replacement therapy for trans women feminizes fat distribution and breasts. Laser hair removal or electrolysis removes excess hair for trans women. Surgical procedures for trans women feminize the voice, skin, face, adam's apple, breasts, waist, buttocks, and genitals. Surgical procedures for trans men masculinize the chest and genitals and remove the womb, ovaries, and fallopian tubes. The acronyms "GRS" and "SRS" refer to genital surgery. The term "sex reassignment therapy" (SRT) is used as an umbrella term for physical procedures required for transition. Use of the term "sex change" has been criticized for its emphasis on surgery, and the term "transition" is preferred.^[9][96] Availability of these procedures depends on degree of gender dysphoria, presence or absence of gender identity disorder,^[74] and standards of care in the relevant jurisdiction.

Trans men who have not had a hysterectomy and who take testosterone are at increased risk for endometrial cancer because androstenedione, which is made from testosterone in the body, can be converted into estrogen, and external estrogen is a risk factor for endometrial cancer.^[98]

Legal procedures exist in some jurisdictions which allow individuals to change their legal gender or name to reflect their gender identity. Requirements for these procedures vary from an explicit formal diagnosis of transsexualism, to a diagnosis of gender identity disorder, to a letter from a physician that attests the individual's gender transition or having established a different gender role.^[99] In 1994, the DSM IV entry was changed from "Transsexual" to "Gender Identity Disorder". In many places, transgender people are not legally protected from discrimination in the workplace or in public accommodations.^[23] A report released in February 2011 found that 90% of transgender people faced discrimination at work and were unemployed at double the rate of the general population,^[21] and over half had been harassed or turned away when attempting to access public services.^[21] Members of the transgender community also encounter high levels of discrimination in health care.^[100]

36 countries in Europe require a mental health diagnosis for legal gender recognition and 20 countries still require sterilisation.^[101] In April 2017, the European Court of Human Rights ruled that requiring sterilisation for legal gender recognition violates human rights.^[102] All Council of Europe Member States must bring their legislation and practice into line with this new legal principle.

Since 2014 it has been possible for adults without the requirement of a psychiatric evaluation, medical or surgical treatment, divorce or castration, to after a six-month ‘reflection period’ have their social security number changed and legally change gender.^[103][104] However, a person must still bear a gender equivalent or neutral name and may be required to a name change.

In November 2017, the Federal Constitutional Court ruled that the civil status law must allow a third gender option.^[105] Thus officially recognising "third sex" meaning that birth certificates will not have blank gender entries for intersex people. The ruling came after an intersex person, who is neither a man nor woman according to chromosomal analysis, brought a legal challenge after attempting to change their registered sex to "inter" or divers.^[106]

Jurisdiction over legal classification of sex in Canada is assigned to the provinces and territories.

This includes legal change of gender classification.

On June 19, 2017 Bill C-16, after having passed the legislative process in the House of Commons of Canada and the Senate of Canada, became law upon receiving Royal Assent which put it into immediate force.^{[107][108][109]} The law updated the Canadian Human Rights Act and the Criminal Code to include "gender identity and gender expression" as protected grounds from discrimination, hate publications and advocating genocide. The bill also added "gender identity and expression" to the list of aggravating factors in sentencing, where the accused commits a criminal offence against an individual because of those personal characteristics. Similar transgender laws also exist in all the provinces and territories.

In the United States, a federal bill to protect workers from discrimination based on sexual orientation and gender identity, the Employment Non-Discrimination Act, has stalled and failed several times over the past two decades.^[110] Individual states and cities have begun passing their own non-discrimination ordinances.

In New York, for example, Governor David Paterson signed into law New York's first statute to include transgender protections in September 2010.^[111]

Nicole Maines, a trans girl, took a case to Maine's Supreme Court in June, 2013. She argued that being denied access to her high school's women's restroom was a violation of Maine's Human Rights Act; one state judge has disagreed with her,^[112] but Maines won her lawsuit against the Orono school district in January 2014 before the Maine Supreme Judicial Court.^[113] On May 14, 2016, the United States Department of Education and Department of Justice issued guidance directing public schools to allow transgender students to use bathrooms that match their gender identities.^[114]

On June 30, 2016, the United States Department of Defense removed the ban that prohibited transgender people from openly serving in the US military.^[115] On July 27, 2017, President Donald Trump tweeted that transgender Americans will not be allowed to serve "in any capacity" in the United States Armed Forces.^[116] Later that day, Joint Chiefs of Staff Chairman Joseph Dunford announced, "there will be no modifications to the current policy until the president’s direction has been received by the Secretary of Defense and the secretary has issued implementation guidance."^[117]

In California, the School Success and Opportunity Act authored by Assemblyman Tom Ammiano, which became state law on January 1, 2014, says "A pupil shall be permitted to participate in sex-segregated school programs and activities, including athletic teams and competitions, and use facilities consistent with his or her gender identity, irrespective of the gender listed on the pupil's records."^[118][119]

In April 2014, the Supreme Court of India declared transgender to be a 'third gender' in Indian law.^{[120][121][122]} The transgender community in India (made up of Hijras and others) has a long history in India and in Hindu mythology.^[123][124] Justice KS Radhakrishnan noted in his decision that, "Seldom, our society realizes or cares to realize the trauma, agony and pain which the members of Transgender community undergo, nor appreciates the innate feelings of the members of the Transgender community, especially of those whose mind and body disown their biological sex", adding:

Hijras face structural discrimination including not being able to obtain driving licenses, and being prohibited from accessing various social benefits.

It is also common for them to be banished from communities.^[126]

The Roman Catholic Church has been involved in the outreach to LGBT community for several years and continues doing so through Franciscan urban outreach centers, for example, the Open Hearts outreach in Hartford, Connecticut.^[127]

Some feminists and feminist groups are supportive of transgender people.

Others are not.

Though second-wave feminism argued for the sex and gender distinction, some feminists believed there was a conflict between transgender identity and the feminist cause; e.g., they believed that male-to-female transition abandoned or devalued female identity and that transgender people embraced traditional gender roles and stereotypes. Many transgender feminists, however, view themselves as contributing to feminism by questioning and subverting gender norms. Third-wave and contemporary feminism are generally more supportive of transgender people.^[128]

A study of Swedes estimated a ratio of 1.4:1 trans women to trans men for those requesting sex reassignment surgery and a ratio of 1:1 for those who proceeded.^[129]

The causes of transsexuality have been studied for decades.

The most studied factors are biological.

Certain brain structures in trans women have been found to be similar to cisgender women's as opposed to cis men's, and trans men's have been found to be similar to cis men's, even controlling for hormone use, which can also cause trans people's brains to become closer to those of cis people of the same gender. However, these studies are limited as they include a small number of tested individuals.^[130] Brain structure differences have also been part of extensive research on biology and sexual orientation. Studies have also found that both androphilic and gynephilic trans women's brain function and responses are like cis women's and unlike cis men's, or are intermediate between the two. Likewise, studies such as Rametti's have found that trans men have male-like white matter patterns (even before using hormones), regardless of sexual orientation.

Studies of twins suggest that there are likely genetic causes of transsexuality, although the precise genes involved are not fully understood.^[131][132] One study published in the International Journal of Transgenderism found that 33% of identical twin pairs were both trans, compared to only 2.6% of non-identical twins who were raised in the same family at the same time, but were not genetically identical.^[132] A study by Hare reported that trans women have a longer androgen receptor gene than cis men, which is less effective at binding testosterone, potentially preventing complete masculinization of the brain (prenatal androgen exposure or sensitivity, or lack thereof, is an often cited mechanism to explain observed brain-structure differences).^[133] A study by Bentz found that trans men have a CYP17 allele distribution like cis men and unlike cis women.^[134]

Environmental factors have also been proposed.

The failure of an attempt to raise David Reimer from infancy through adolescence as a girl after his genitals were accidentally mutilated is cited as disproving the theory that gender identity is determined by upbringing.

Ray Blanchard created a taxonomy of male-to-female transsexualism that proposes two distinct etiologies for androphilic and gynephilic individuals that has become highly controversial, supported by J. Michael Bailey, Anne Lawrence, James Cantor, Richard F. Docter and others, but opposed by Charles Allen Moser, Larry Nuttbrock, Julia Serano, and the World Professional Association for Transgender Health.

According to Amnesty International, 1.5 million transgender people live in the European Union, making up 0.3% of the population.^[135]

A 2011 survey conducted by the Equality and Human Rights Commission in the UK found that of 10,026 respondents, 1.4% would be classified into a gender minority group. The survey also showed that 1% had gone through any part of a gender reassignment process (including thoughts or actions).^[136]

The 2017 survey of Canadian LGBT+ people called LGBT+ Realities Survey found that of the 1,897 respondents 11% identified as transgender (7% binary transgender, 4% non-binary transgender) and 1% identified as non-binary outside of the transgender umbrella.^[137] The Trans PULSE survey conducted in 2009 and 2010 suggest that as many as 1 in 200 adults may be trans (transgender, transsexual, or transitioned) in the Canadian province of Ontario,^[138] and the 2019 survey of the Two-Spirit and LGBTQ+ population in the Canadian city of Hamilton, Ontario called Mapping the Void: Two-Spirit and LGBTQ+ Experiences in Hamilton showed that 27.6% of the 906 respondents identified as transgender.^[139]

The Social Security Administration, since 1936, has tracked the sex of citizens.^[140] Using this information, along with the Census data, Benjamin Cerf Harris tracked the prevalence of citizens changing to names associated with the opposite sex or changing sex marker.

Harris found that such changes had occurred as early as 1936.

He estimated that 89,667 individuals included in the 2010 Census had changed to an opposite-gendered name, 21,833 of whom had also changed sex marker.^[140] Prevalence in the States varied, from 1.4 to 10.6 per 100,000.^[140] While most people legally changed both name and sex, about a quarter of people changed name, and then five years later changed sex.^[140] An earlier estimate in 1968, by Ira B. Pauly, estimated that about 2,500 transsexual people were living in the United States, with four times as many trans women as trans men.^[141]

One effort to quantify the population in 2011 gave a "rough estimate" that 0.3% of adults in the US are transgender.^[142][143] More recent studies released in 2016 estimate the proportion of Americans who identify as transgender at 0.5 to 0.6%. This would put the total number of transgender Americans at approximately 1.4 million adults (as of 2016).^{[144][145][146][147]}

In Latin American cultures, a travesti is a person who has been assigned male at birth and who has a feminine, transfeminine, or "femme" gender identity. Travestis generally undergo hormonal treatment, use female gender expression including new names and pronouns from the masculine ones they were given when assigned a sex, and might use breast implants, but they are not offered or do not desire sex-reassignment surgery. Travesti might be regarded as a gender in itself (a "third gender"), a mix between man and woman ("intergender/androgynes"), or the presence of both masculine and feminine identities in a single person ("bigender"). They are framed as something entirely separate from transgender women, who possess the same gender identity of people assigned female at birth.

Other transgender identities are becoming more widely known, as a result of contact with other cultures of the Western world.^[148] These newer identities, sometimes known under the umbrella use of the term "genderqueer",^[148] along with the older travesti term, are known as non-binary and go along with binary transgender identities (those traditionally diagnosed under the now obsolete label of "transsexualism") under the single umbrella of transgender, but are distinguished from cross-dressers and drag queens and kings, that are held as nonconforming gender expressions rather than transgender gender identities when a distinction is made.^[149]

Deviating from the societal standards for sexual behavior, sexual orientation/identity, gender identity, and gender expression have a single umbrella term that is known as sexodiverso or sexodiversa in both Spanish and Portuguese, with its most approximate translation to English being "queer".

In Thailand and Laos,^[150] the term kathoey is used to refer to male-to-female transgender people^[151] and effeminate gay men.^[152] Transgender people have also been documented in Iran,^[153] Japan,^[154] Nepal,^[153] Indonesia,^[150] Vietnam,^[150] South Korea,^[158] Singapore,^[159] and the greater Chinese region, including Hong Kong,^[160][161] Taiwan,^[162] and the People's Republic of China.^{[163][164][165]}

The cultures of the Indian subcontinent include a third gender, referred to as hijra in Hindi. In India, the Supreme Court on April 15, 2014, recognized a third gender that is neither male nor female, stating "Recognition of transgenders as a third gender is not a social or medical issue but a human rights issue."^[166] On January 5, 2015, Reuters stated that the first transgender mayor was elected in central India.^[167]

In what is now the United States and Canada, many Native American and First Nations peoples recognized the existence of more than two genders,^[168] such as the Zuñi male-bodied Ła'mana,^[169] the Lakota male-bodied winkte,^[170] and the Mohave male-bodied alyhaa and female-bodied hwamee.^[171] Such people were previously^[172] referred to as berdache but are now referred to as Two-Spirit,^[173] and their spouses would not necessarily have been regarded as gender-different.^[171] In Mexico, the Zapotec culture includes a third gender in the form of the Muxe.^[174]

Among the ancient Middle Eastern Akkadian people, a salzikrum was a person who appeared biologically female but had distinct male traits. Salzikrum is a compound word meaning male daughter. According to the Code of Hammurabi, salzikrūm had inheritance rights like that of priestesses; they inherited from their fathers, unlike regular daughters. A salzikrum's father could also stipulate that she inherit a certain amount.^[175] In Ancient Rome, the Gallae were castrated^[176] followers of the Phrygian goddess Cybele and can be regarded as transgender in today's terms.^[177][178]

In early Medina, gender-variant^[179] male-to-female Islamic people were acknowledged^[180] in the form of the Mukhannathun.

Mahu is a traditional status in Polynesian cultures. Also, in Fa'asamoa traditions, the Samoan culture allows a specific role for male to female transgender individuals as Fa'afafine.

Transgender people vary greatly in choosing when, whether, and how to disclose their transgender status to family, close friends, and others.

The prevalence of discrimination^[181] and violence (transgender people are 28% more likely to be victims of violence)^[182] against transgender persons can make coming out a risky decision. Fear of retaliatory behavior, such as being removed from the parental home while underage, is a cause for transgender people to not come out to their families until they have reached adulthood.^[183] Parental confusion and lack of acceptance of a transgender child may result in parents treating a newly revealed gender identity as a "phase" or making efforts to change their children back to "normal" by utilizing mental health services to alter the child's gender identity.^[184][185]

The internet can play a significant role in the coming out process for transgender people.

Some come out in an online identity first, providing an opportunity to go through experiences virtually and safely before risking social sanctions in the real world.^[186]

As more transgender people are represented and included within the realm of mass culture, the stigma that is associated with being transgender can influence the decisions, ideas, and thoughts based upon it.

Media representation, culture industry, and social marginalization all hint at popular culture standards and the applicability and significance to mass culture as well. These terms play an important role in the formation of notions for those who have little recognition or knowledge of transgender people. Media depictions represent only a minuscule spectrum of the transgender group,^[187] which essentially conveys that those that are shown are the only interpretations and ideas society has of them.

However, in 2014, the United States reached a "transgender tipping point", according to Time.^[188][189] At this time, the media visibility of transgender people reached a level higher than seen before. Since then, the number of transgender portrayals across TV platforms has stayed elevated.^[190] Research has found that viewing multiple transgender TV characters and stories improves viewers' attitudes toward transgender people and related policies.^[191]

International Transgender Day of Visibility is an annual holiday occurring on March 31^[192][193] dedicated to celebrating transgender people and raising awareness of discrimination faced by transgender people worldwide. The holiday was founded by Michigan-based transgender activist^[194] Rachel Crandall in 2009^[195] as a reaction to the lack of LGBT holidays celebrating transgender people, citing the frustration that the only well-known transgender-centered holiday was the Transgender Day of Remembrance which mourned the loss of transgender people to hate crimes, but did not acknowledge and celebrate living members of the transgender community.

Transgender Awareness Week is a one-week celebration leading up to Transgender Day of Remembrance.

The purpose of Transgender Awareness Week is to educate about transgender and gender non-conforming people and the issues associated with their transition or identity.^[196]

Transgender Day of Remembrance (TDOR) is held every year on November 20 in honor of Rita Hester, who was killed on November 28, 1998, in an anti-transgender hate crime. TDOR serves a number of purposes:

Annual marches, protests or gatherings take place around the world for transgender issues, often taking place during the time of local Pride parades for LGBT people. These events are frequently organised by trans communities to build community, address human rights struggles, and create visibility.

A common symbol for the transgender community is the Transgender Pride Flag, which was designed by the American transgender woman Monica Helms in 1999, and was first shown at a pride parade in Phoenix, Arizona in 2000. The flag consists of five horizontal stripes: light blue, pink, white, pink, and light blue. Helms describes the meaning of the flag as follows:

Other transgender symbols include the butterfly (symbolizing transformation or metamorphosis),^[199] and a pink/light blue yin and yang symbol. Several gender symbols have been used to represent transgender people, including ⚥ and ⚧.^[200][201]