Research has shown that paraphilias are rarely observed in women. However, there have been some studies on females with paraphilias. Sexual masochism has been found to be the most commonly observed paraphilia in women, with approximately 1 in 20 cases of sexual masochism being female.

Many acknowledge the scarcity of research on female paraphilias. The majority of paraphilia studies are conducted on people who have been convicted of sex crimes. Since the number of male convicted sex offenders far exceeds the number of female convicted sex offenders, research on paraphilic behavior in women is consequently lacking. Some researchers argue that an underrepresentation exists concerning pedophilia in females. Due to the low number of women in studies on pedophilia, most studies are based from "exclusively male samples". This likely underrepresentation may also be attributable to a "societal tendency to dismiss the negative impact of sexual relationships between young boys and adult women". Michele Elliott has done extensive research on child sexual abuse committed by females, publishing the book "Female Sexual Abuse of Children: The Last Taboo" in an attempt to challenge the gender-biased discourse surrounding sex crimes. John Hunsley states that physiological limitations in the study of female sexuality must also be acknowledged when considering research on paraphilias. He states that while a man's sexual arousal can be directly measured from his erection (see penile plethysmograph), a woman's sexual arousal cannot be measured as clearly (see vaginal photoplethysmograph), and therefore research concerning female sexuality is rarely as conclusive as research on men.

The prevalence of pedophilia in the general population is not known, but is estimated to be lower than 5% among adult men. Less is known about the prevalence of pedophilia in women, but there are case reports of women with strong sexual fantasies and urges towards children. Most sexual offenders against children are male. Females may account for 0.4% to 4% of convicted sexual offenders, and one study estimates a 10 to 1 ratio of male-to-female child molesters. The true number of female child molesters may be underrepresented by available estimates, for reasons including a "societal tendency to dismiss the negative impact of sexual relationships between young boys and adult women, as well as women's greater access to very young children who cannot report their abuse", among other explanations.

The term "pedophile" is commonly used by the public to describe all child sexual abuse offenders. This usage is considered problematic by researchers, because many child molesters do not have a strong sexual interest in prepubescent children, and are consequently not pedophiles. There are motives for child sexual abuse that are unrelated to pedophilia, such as stress, marital problems, the unavailability of an adult partner, general anti-social tendencies, high sex drive, or alcohol use. As child sexual abuse is not automatically an indicator that its perpetrator is a pedophile, offenders can be separated into two types: pedophilic and non-pedophilic (or preferential and situational). Estimates for the rate of pedophilia in detected child molesters generally range between 25% and 50%. A 2006 study found that 35% of its sample of child molesters were pedophilic. Pedophilia appears to be less common in incest offenders, especially fathers and step-fathers. According to a U.S. study on 2429 adult male sex offenders who were categorized as "pedophiles", only 7% identified themselves as exclusive; indicating that many or most child sexual abusers may fall into the non-exclusive category.

Some pedophiles do not molest children. Little is known about this population because most studies of pedophilia use criminal or clinical samples, which may not be representative of pedophiles in general. Researcher Michael Seto suggests that pedophiles who commit child sexual abuse do so because of other anti-social traits in addition to their sexual attraction. He states that pedophiles who are "reflective, sensitive to the feelings of others, averse to risk, abstain from alcohol or drug use, and endorse attitudes and beliefs supportive of norms and the laws" may be unlikely to abuse children. A 2015 study indicates that pedophiles who molested children are neurologically distinct from non-offending pedophiles. The pedophilic molesters had neurological deficits suggestive of disruptions in inhibitory regions of the brain, while non-offending pedophiles had no such deficits.

According to Abel, Mittleman, and Becker (1985) and Ward "et al." (1995), there are generally large distinctions between the characteristics of pedophilic and non-pedophilic molesters. They state that non-pedophilic offenders tend to offend at times of stress; have a later onset of offending; and have fewer, often familial, victims, while pedophilic offenders often start offending at an early age; often have a larger number of victims who are frequently extrafamilial; are more inwardly driven to offend; and have values or beliefs that strongly support an offense lifestyle. One study found that pedophilic molesters had a median of 1.3 victims for those with girl victims and 4.4 for those with boy victims. Child molesters, pedophilic or not, employ a variety of methods to gain sexual access to children. Some groom their victims into compliance with attention and gifts, while others use threats, alcohol or drugs, or physical force.

Although what causes pedophilia is not yet known, researchers began reporting a series of findings linking pedophilia with brain structure and function, beginning in 2002. Testing individuals from a variety of referral sources inside and outside the criminal justice system as well as controls, these studies found associations between pedophilia and lower IQs, poorer scores on memory tests, greater rates of non-right-handedness, greater rates of school grade failure over and above the IQ differences, lesser physical height, greater probability of having suffered childhood head injuries resulting in unconsciousness, and several differences in MRI-detected brain structures. They report that their findings suggest that there are one or more neurological characteristics present at birth that cause or increase the likelihood of being pedophilic. Some studies have found that pedophiles are less cognitively impaired than non-pedophilic child molesters. A 2011 study reported that pedophilic child molesters had deficits in response inhibition, but no deficits in memory or cognitive flexibility. Evidence of familial transmittability "suggests, but does not prove that genetic factors are responsible" for the development of pedophilia. A 2015 study indicated that pedophilic offenders have a normal IQ.

Another study, using structural MRI, indicated that male pedophiles have a lower volume of white matter than a control group. Functional magnetic resonance imaging (fMRI) has indicated that child molesters diagnosed with pedophilia have reduced activation of the hypothalamus as compared with non-pedophilic persons when viewing sexually arousing pictures of adults. A 2008 functional neuroimaging study notes that central processing of sexual stimuli in heterosexual "paedophile forensic inpatients" may be altered by a disturbance in the prefrontal networks, which "may be associated with stimulus-controlled behaviours, such as sexual compulsive behaviours". The findings may also suggest "a dysfunction at the cognitive stage of sexual arousal processing".

Blanchard, Cantor, and Robichaud (2006) reviewed the research that attempted to identify hormonal aspects of pedophiles. They concluded that there is some evidence that pedophilic men have less testosterone than controls, but that the research is of poor quality and that it is difficult to draw any firm conclusion from it.

While not causes of pedophilia themselves, childhood abuse by adults or comorbid psychiatric illnesses—such as personality disorders and substance abuse—are risk factors for acting on pedophilic urges. Blanchard, Cantor, and Robichaud addressed comorbid psychiatric illnesses that, "The theoretical implications are not so clear. Do particular genes or noxious factors in the prenatal environment predispose a male to develop both affective disorders and pedophilia, or do the frustration, danger, and isolation engendered by unacceptable sexual desires—or their occasional furtive satisfaction—lead to anxiety and despair?" They indicated that, because they previously found mothers of pedophiles to be more likely to have undergone psychiatric treatment, the genetic possibility is more likely.

A study analyzing the sexual fantasies of 200 heterosexual men by using the Wilson Sex Fantasy Questionnaire exam determined that males with a pronounced degree of paraphilic interest (including pedophilia) had a greater number of older brothers, a high 2D:4D digit ratio (which would indicate low prenatal androgen exposure), and an elevated probability of being left-handed, suggesting that disturbed hemispheric brain lateralization may play a role in deviant attractions.

Paraphilia (previously known as sexual perversion and sexual deviation) is the experience of intense sexual arousal to atypical objects, situations, fantasies, behaviors, or individuals. Such attraction may be labeled sexual fetishism. No consensus has been found for any precise border between unusual sexual interests and paraphilic ones. There is debate over which, if any, of the paraphilias should be listed in diagnostic manuals, such as the "Diagnostic and Statistical Manual of Mental Disorders" (DSM) or the International Classification of Diseases (ICD).

The number and taxonomy of paraphilia is under debate; one source lists as many as 549 types of paraphilia. The DSM-5 has specific listings for eight paraphilic disorders. Several sub-classifications of the paraphilias have been proposed, and some argue that a fully dimensional, spectrum or complaint-oriented approach would better reflect the evidence.

Sexual sadism disorder is the condition of experiencing sexual arousal in response to the extreme pain, suffering or humiliation of others. Several other terms have been used to describe the condition, and the condition may overlap with other conditions that involve inflicting pain. It is distinct from situations in which consenting individuals use mild or simulated pain or humiliation for sexual excitement. The words "sadism" and "" are derived from Marquis de Sade.

With paraphilic coercive disorder, the individual employs enough force to subdue a victim, but with sexual sadism disorder, the individual often continues to inflict harm regardless of the compliance of the victim, which sometimes escalates not only to the death of the victim, but also to the mutilation of the body. What is experienced by the sadist as sexual does not always appear obviously sexual to non-sadists: Sadistic rapes do not necessarily include penile penetration of the victim. In a survey of offenses, 77% of cases included sexual bondage, 73% included anal rape, 60% included blunt force trauma, 57% included vaginal rape, and 40% included penetration of the victim by a foreign object. Moreover, in 40% of cases, the offender kept a personal item of the victim as a souvenir.

On personality testing, sadistic rapists apprehended by law enforcement have shown elevated traits of impulsivity, hypersexuality, callousness, and psychopathy.

Although there appears to be a continuum of severity from mild ("hyperdominance" or "BDSM") to moderate ("paraphilic coercive disorder") to severe ('sexual sadism disorder), it is not clear if they are genuinely related or only appear related superficially.

Very little is known about how sexual sadism disorder develops. Most of the people diagnosed with sexual sadism disorder come to the attention of authorities by committing sexually motivated crimes. Surveys have also been conducted including people who are interested in only mild and consensual forms of sexual pain/humiliation (BDSM).

Most of the people with full-blown sexual sadism disorder are male, whereas the sex ratio of people interested in BDSM is closer to 2:1 male-to-female.

People with sexual sadism disorder" are at an elevated likelihood of having other paraphilic sexual interests.

Erotophobia is a term coined by a number of researchers in the late 1970s and early 1980s to describe one pole on a continuum of attitudes and beliefs about sexuality. The model of the continuum is a basic polarized line, with erotophobia (fear of sex or negative attitudes about sex) at one end and erotophilia (positive feelings or attitudes about sex) at the other end.

The word erotophobia is derived from the name of Eros, the Greek god of erotic love, and Phobos, Greek (φόβος) for "fear".

As a clinical phobia, 'erotophobia' describes an irrational and potentially debilitating fear of some object, person or act that is related to sex. This fear either impairs a person's desire or ability to have sexual relationships, or completely prevents a person's ability to have sex. Erotophobia can also in some (but not all) individual cases, be a part of larger patterns of any of the following psychological problems—social phobia, avoidant personality disorder, body dysmorphic disorder, or general social anxiety problems. Erotophobia can also, for others, be very specific to love making with another person and not be related to any of these other social anxiety disorders. In the case of "specific" erotophobia, only the fear of something related to sex would be present without any other fears or syndromes.

Sexual maturation disorder is a disorder of anxiety or depression related to an uncertainty about one's gender identity or sexual orientation. The World Health Organization (WHO) lists sexual maturation disorder in the ICD-10, under "Psychological and behavioural disorders associated with sexual development and orientation".

Sexual orientation, by itself, is not a disorder and is not classified under this heading. It differs from ego-dystonic sexual orientation where the sexual orientation or gender identity is repressed or denied.

As the disorder progresses in life, it can increase in severity, and cause other behaviors or actions in late adolescence and adulthood. “A strong and persistent cross-gender identification in adolescents and adults [can cause a] disturbance manifested by symptoms such as a stated desire to be the other sex, frequent passing as the other sex, desire to live or be treated as the other sex, or the conviction that he or she has the typical feelings and reactions of the other sex” (APA, 2000). This can cause severe conflict for the individual living in a society which endorses and enforces adherence to strict gender roles. In a more persistent disassociation with one’s own body or gender, someone can go to more extreme lengths to feel as though they are fulfilled or satisfied with themselves. This can lead these individuals to engage in behavior that displaces their emotions. These individuals may also seek to undergo sex reassignment surgery. “Persistent discomfort with his or her sex or sense of inappropriateness in the gender role of that sex in adolescents and adults [can cause a] disturbance manifested by symptoms such as preoccupation with getting rid of primary and secondary sex characteristics (e.g., request for hormones, surgery, or other procedures to physically alter sexual characteristics to simulate the other sex) or belief that he or she was born the wrong sex” (APA, 2000).

Gender dysphoria in children or gender identity disorder in children (GIDC) is a formal diagnosis used by psychologists and physicians to describe children who experience significant discontent (gender dysphoria) with their biological sex, assigned gender, or both.

GIDC was formalized in the third revision of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-III) in 1980 and primarily referenced gender non-conforming behaviors. GIDC remained in the DSM from 1980 to 2013, when it was replaced with the diagnosis of "gender dysphoria" in the fifth revision (DSM-5), in an effort to diminish the stigma attached to gender variance while maintaining a diagnostic route to gender affirming medical interventions such as hormone therapy and surgery.

Controversy surrounding the pathologization and treatment of cross-gender identity and behaviors, particularly in children, has been evident in the literature since the 1980s. Proponents of more widespread GIDC diagnoses argue that therapeutic intervention helps children be more comfortable in their bodies and can prevent adult gender identity disorder. Opponents say that the equivalent therapeutic interventions with gays and lesbians (titled conversion or reparative therapy) have been strongly questioned or declared unethical by the American Psychological Association, American Psychiatric Association, American Association of Social Workers and American Academy of Pediatrics. The World Professional Association for Transgender Health (WPATH) states that treatment aimed at trying to change a person's gender identity and expression to become more congruent with sex assigned at birth "is no longer considered ethical." Critics also argue that the GIDC diagnosis and associated therapeutic interventions rely on the assumption that an adult transsexual identity is undesirable, challenging this assumption along with the lack of clinical data to support outcomes and efficacy.

Gender identity disorder in children is more heavily linked with adult homosexuality than adult transsexualism. According to limited studies, the majority of children diagnosed with GID cease to desire to be the other sex by puberty, with most growing up to identify as gay or lesbian with or without therapeutic intervention.

Children with persistent GID are characterized by more extreme gender dysphoria in childhood than children with desisting gender dysphoria. Some (but not all) gender diverse / gender independent / gender fluid youth will want or need to transition, which may involve social transition (changing dress, name, pronoun), and, for older youth and adolescents, medical transition (hormonal and surgical intervention). Treatment may take the form of puberty blockers such as Lupron Depot or Leuprolide Acetate, or cross-sex hormones (i.e., administering estrogen to an assigned male at birth or testosterone to an assigned female at birth), or surgery (i.e., mastectomies, salphingo-oophorectomies/hysterectomy, the creation of a neophallus in female-to-male transsexuals, orchiectomies, breast augmentation, facial feminization surgery, the creation of a neovagina in male-to-female transsexuals), with the aim of bringing one’s physical body in line with their felt gender. The ability to transition (socially and medically) are sometimes needed in the treatment of gender dysphoria.

The Endocrine Society does not recommend endocrine treatment of prepubertal children because clinical experience suggests that GID can be reliably assessed only after the first signs of puberty. It recommends treating transsexual adolescents by suppressing puberty with puberty blockers until age 16 years old, after which cross-sex hormones may be given.

The University of Washington is leading the largest study of transgender youth ever conducted. The study, known as the Transgender Youth Project, looks at 300 transgender kids between the ages of 3 and 12. Researchers hope to follow the children for 20 years.

Gynophobia or gynephobia is an abnormal fear of women, a type of specific social phobia. In the past, the Latin term horror feminae was used.

Gynophobia should not be confused with misogyny, the hatred, contempt for and inveterate prejudice against women, although some may use the terms interchangeably, in reference to the social, rather than pathological aspect of negative attitudes towards women.

An antonym is philogyny, the love, respect for and admiration of women.

According to a systematic review from 2014, prevalence rates of sexual addiction and related sexual disorders ranges from 3% to 6%.

Sexual addiction, also known as sex addiction, is a state characterized by [[compulsive]] participation or engagement in [[Human sexual activity|sexual activity]], particularly [[sexual intercourse]], despite negative consequences. Proponents of a [[diagnostic model]] for sexual addiction, as defined here, consider it to be one of several sex-related disorders within an umbrella concept known as [[hypersexual disorder]]. The term "sexual dependence" is also used to refer to people who report being unable to control their [[sexual urges]], behaviors, or thoughts. Related models of pathological sexual behavior include [[hypersexuality]] (nymphomania and satyriasis), [[erotomania]], [[Don Juanism]] (or Don Juanitaism), and [[paraphilia]]-related disorders.

The concept of sexual addiction is contentious. There is considerable debate amongst [[psychiatrists]], psychologists, [[sexologist]]s, and other specialists whether compulsive sexual behavior constitutes an addiction, and therefore its classification and possible diagnosis. , sexual addiction is not a clinical diagnosis in either the [[Diagnostic and Statistical Manual of Mental Disorders|DSM]] or [[International Statistical Classification of Diseases and Related Health Problems|ICD]] medical classifications of diseases and medical disorders. Some argue that applying such concepts to normal behaviors such as sex, can be problematic, and suggest that applying medical models such as addiction to human sexuality can serve to [[Slut-shaming|pathologise normal behavior]] and cause harm

Neuroscientists, pharmacologists, molecular biologists, and other researchers in related fields have identified the [[transcription factor|transcriptional]] and [[epigenetic]] mechanisms of addiction [[pathophysiology]]. Diagnostic models, which use the pharmacological model of addiction (this model associates addiction with drug-related concepts, particularly [[physical dependence]], [[drug withdrawal]], and [[drug tolerance]]), do not currently include diagnostic criteria to identify sexual addictions in a clinical setting. In the brain disease model of addiction, which uses neuropsychological concepts to characterize addictions, sexual addictions are identifiable and well-characterized. In this model, [[addictive drugs]] are characterized as those which are both [[reinforcing]] and [[reward system|rewarding]]. Addictive behaviors (those which can induce a compulsive state) are similarly identified and characterized by their rewarding and reinforcing properties.

In "Sexual Addiction and Compulsivity", authors Taylor and Francis argue that: "Obsessive sexual behavior illness is defined by a continual pattern of failure to control intense, repetitive sexual impulses or urges."

Transsexual people experience a gender identity that is inconsistent with, or not culturally associated with, their assigned sex, and desire to permanently transition to the gender with which they identify, usually seeking medical assistance (including hormone replacement therapy and other sex reassignment therapies) to help them align their body with their identified sex or gender.

"Transsexual" is generally considered a subset of "transgender", but some transsexual people reject the label of "transgender". A medical diagnosis of gender dysphoria can be made if a person expresses a desire to live and be accepted as a member of their identified sex, and if a person experiences impaired functioning or distress as a result of their gender identity.

A non-operative transsexual person, or non-op, is someone who has not had SRS, and does not intend to have it in the future. There can be various reasons for this, from the personal to the financial.

Katoptronophilia is a paraphilia for mirrors (the Greek word for "mirror" is "katoptron"). It may include activities such as having sex in front of mirrors, masturbating in front of mirrors, enacting other paraphilias in front of a mirror, having an orgy in front of a mirror, or enacting stripping fetishism in front of mirrors.

Enacting katoptronophiliac fantasies may involve constructing environments for erotic activity in which one is completely surrounded by mirrors, sometimes including even on the ceiling. A person who is a "katoptronophiliac" may put mirrors all over their house so they can have sex in any room in the house.

Many pornographic films show porn stars having sex in front of mirrors.

Many people enjoy having sex in front of mirrors and have mirrors in their bedrooms in which they can watch themselves have sex. They sometimes engage in this activity for their personal enjoyment. On a deeper level this could relate to the person's need to reflect and critique themselves, and also being on a mental state of narcissism. The person often is solely absorbed in themselves and likes to watch their actions so as to admire.

DSDs are medical conditions involving the way the reproductive system develops from infancy (and before birth) through young adulthood. There are several types of DSDs and their effect on the external and internal reproductive organs varies greatly.

A frequently-used social and medical adjective for people with DSDs is "intersex". Parents with DSD children and clinicians involved in DSD treatment usually try to make clear distinctions between biological sex, social gender, and sexual orientation. This helps reduce confusion about the differences between being intersex, being transgender, and being gay/lesbian.

The most common DSD is congenital adrenal hyperplasia (CAH), which results in a person with female (XX) chromosomes having genitals that look somewhat masculine. In mild cases CAH results in a slightly enlarged clitoris, while in more severe cases it can be difficult to decide (just by looking) whether a baby is male or female (this is called having ambiguous genitals). Nevertheless, if they are old enough to know the difference, most children with CAH think of themselves as girls. CAH is caused by a problem with the adrenal glands and is usually treated by taking a daily medication to replace or supplement the missing adrenal hormones. (When this adrenal problem occurs in people with male (XY) chromosomes, the result is over-masculinization and premature puberty).

Another common DSD is androgen insensitivity syndrome (AIS), which means that a person with male (XY) chromosomes does not respond to testosterone in the usual way. This results in a body that to some degree has a feminine appearance. In Complete Androgen Insensitivity Syndrome (CAIS) the result is a totally feminine appearance, including typical female breast development. Consequently, most young women with CAIS are unaware of their condition until the early teen years when they fail to menstruate. In the milder form, called Partial Androgen Insensitivity Syndrome (PAIS), the genitals can vary from mostly female to almost completely male. Some people with PAIS think of themselves as girls/women, others regard themselves as boys/men, and some consider themselves mixed-gender.

One of the more unusual DSDs is 5-alpha-reductase deficiency (5ARD). It is caused by a shortage early in life of an enzyme that activates testosterone. In this condition, a person with male (XY) chromosomes has a body that appears female before puberty. After puberty begins, other testosterone-activating enzymes become available and the body soon takes on a masculine appearance, with the scrotum and penis usually reaching typical or nearly-typical size. If 5ARD is diagnosed at a young age, the child is often raised as a boy (a 1996 Brazilian study suggested that the majority of adults with this condition consider themselves men but this has been questioned in some more recent research).

In addition to CAH, CAIS, PAIS, and 5ARD there are several rarer types of DSDs, and in some cases it is not possible to make a clear diagnosis of the underlying condition.

The penis and clitoris are essentially the same organ (differing only in size, and generically called the phallus). In typical males, the urethra is located at the tip of the penis, while in typical females the urethra is located below the base of the clitoris. When the phallus is of intermediate size, it is possible also to have a urethral opening located along the shaft; this condition is known as hypospadias.

Open-minded parenting, appropriate and conservative medical intervention, and age-appropriate child involvement in the treatment plan contribute greatly to successful outcomes for the entire range of DSDs.

According to the UN Office of the High Commissioner for Human Rights:

In biological terms, sex may be determined by a number of factors present at birth, including:

- the number and type of sex chromosomes;

- the type of gonads—ovaries or testicles;

- the sex hormones;

- the internal reproductive anatomy (such as the uterus in females); and

- the external genitalia.

People whose characteristics are not either all typically male or all typically female at birth are intersex.

Some intersex traits are not always visible at birth; some babies may be born with ambiguous genitals, while others may have ambiguous internal organs (testes and ovaries). Others will not become aware that they are intersex unless they receive genetic testing, because it does not manifest in their phenotype.

The common pathway of sexual differentiation, where a productive human female has an XX chromosome pair, and a productive male has an XY pair, is relevant to the development of intersex conditions.

During fertilization, the sperm adds either an X (female) or a Y (male) chromosome to the X in the ovum. This determines the genetic sex of the embryo. During the first weeks of development, genetic male and female fetuses are "anatomically indistinguishable", with primitive gonads beginning to develop during approximately the sixth week of gestation. The gonads, in a "bipotential state", may develop into either testes (the male gonads) or ovaries (the female gonads), depending on the consequent events. Through the seventh week, genetically female and genetically male fetuses appear identical.

At around eight weeks of gestation, the gonads of an XY embryo differentiate into functional testes, secreting testosterone. Ovarian differentiation, for XX embryos, does not occur until approximately Week 12 of gestation. In normal female differentiation, the Müllerian duct system develops into the uterus, Fallopian tubes, and inner third of the vagina.

In males, the Müllerian duct-inhibiting hormone MIH causes this duct system to regress. Next, androgens cause the development of the Wolffian duct system, which develops into the vas deferens, seminal vesicles, and ejaculatory ducts.

By birth, the typical fetus has been completely "sexed" male or female, meaning that the genetic sex (XY-male or XX-female) corresponds with the phenotypical sex; that is to say, genetic sex corresponds with internal and external gonads, and external appearance of the genitals.

Disorders of sex development (DSD), sometimes referred to as disorders of sex differentiation or differences of sex development, are medical conditions involving the reproductive system. More specifically, these terms refer to "congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical."

The term has been controversial, and research has shown that affected people experience a negative impact, with the terminology impacting choice and utilization of health care providers. The World Health Organization and many medical journals still reference DSDs as intersex traits or conditions. The Council of Europe, and Inter-American Commission on Human Rights have called for a review of medical classifications that unnecessarily medicalize intersex traits.

Surgery is sometimes performed to alter the appearance of the genitals. However many surgeries performed on intersex people lack clear evidence of necessity, can be considered as mutilating, and are widely considered to be human rights violations when performed without the informed consent of the recipient.

Sex determination and differentiation is generalized with chromosomal sex during fertilization. At early stages, phenotypic sex does not match chromosomal sex—until later during intrauterine development, sexual maturation is reached. During intrauterine development, females change to male with the testes moving down from a blind vaginal pouch with a developing scrotum, as well as a penis which initially resembled a clitoris. What seems like a female phenotype is altered by increased testosterone levels secretion.

Mutations affecting the androgen receptor (AR) gene may cause either complete or partial androgen insensitivity syndrome. Androgen, a hormone used to describe a group of sex steroid hormones, is responsible for affecting male pseudohermaphroditism. The differentiation of the fetus as male takes place during the sixth or seventh week of gestation. The development is directed by the testicular determining factor: the gene SRY (sex determining region on Y chromosome). Throughout 9th to 13th week, the development of a male genitalia is dependent upon the conversion of testosterone to the more potent androgen by the action of 5α-reductase within the target tissues of the genitalia. A type of internal male pseudohermaphroditism is Persistent Müllerian duct syndrome, which is developed through synthesis of Müllerian-inhibiting factor defects. In such instances, duct derivatives are now in 46XY males—this includes the uterus, fallopian tubes, and upper vagina. These individuals with a hernia sac and bowel loops were found with duct derivatives as well as testes.

A study on a male pseudohermaphrodite kitten showed there was a combination of gastrointestinal and urogenital congenital abnormalities. It was confirmed to have type II atresia ani and rectovaginal fistula that is associated with male pseudohermaphroditism.

The Chinese word "zǒuhuǒrùmó" "①be obsessed with sth. ②possessed by the Devil" combines "zǒuhuǒ(r)" "①〈elec.〉 ⓐspark ⓑhave a short circuit ②〈coll.〉 discharge (a firearm) accidentally ③overstate ④catch fire; be on fire" and "rùmó" "①be spellbound ②be infatuated/obsessed". In recent times this syndrome has been known as "qìgōngpiānchā" 氣功偏差 "qigong deviation/error". The term has traditionally been applied to indicate that something has gone wrong in one's martial arts training, interpreted as "imbalance of qi (life energy)". In more recent history, the term has been applied to refer to undesirable somatic or psychological effects experienced during or after the practice of the broad range of Chinese self-cultivation exercises known as qigong. Most cases do not last for an extended period of time, and are never brought to medical attention. While qigong may act as a stressor in vulnerable individuals, relations between qigong and disorders are manifold, and causal relationships have not been demonstrated. Similar syndromes have been observed in other forms of self-cultivation practices such as yoga (Kundalini syndrome), meditation, and hypnosis.