According to the Office of the United Nations High Commissioner for Human Rights, intersex people are born with "any of several sex characteristics including chromosome patterns, gonads, or genitals that... do not fit typical binary notions of male or female bodies."
A person who is born with physical sex characteristics that do not fit typical female/male classifications.
Biological sex: The physical and genetic characteristics that determine whether a person is male or female.
Gender identity: An individual's internal sense of whether they are male or female, or something else altogether.
Gender expression: The outward display of gender identity through behavior, dress, and other forms of self-expression.
Hormones: Chemical messengers in the body that influence sexual development and other physiological processes.
Hermaphroditism: A condition where an individual has both male and female reproductive systems.
Androgen insensitivity syndrome (AIS): A condition where a person with XY chromosomes does not respond to testosterone, resulting in an individual who appears female or intersex at birth.
Congenital adrenal hyperplasia (CAH): A condition where the adrenal glands produce excess androgens, resulting in intersex characteristics in some cases.
Klinefelter syndrome: A condition where an individual is born with an extra X chromosome, resulting in physical differences and atypical hormone levels.
Turner syndrome: A condition where an individual is born with only one X chromosome, resulting in physical differences and hormonal imbalances.
Intersex surgery: Medical procedures performed on intersex individuals to align their physical characteristics with male or female norms.
Non-binary gender: An identity outside of the traditional male/female binary.
Transgender: An individual whose gender identity does not match the sex they were assigned at birth.
Queer: A term used to describe individuals who identify as something other than heterosexual or cisgender.
LGBTQIA+: A collection of identities, including lesbian, gay, bisexual, transgender, queer/questioning, intersex, and asexual.
Androgen insensitivity syndrome (AIS): A condition in which a person with XY chromosomes may be resistant to androgens (male hormones), causing them to develop feminine characteristics.
Congenital adrenal hyperplasia (CAH): A condition in which the adrenal glands produce high levels of male hormones, resulting in ambiguous genitalia in females or premature development of male characteristics in males.
5α-Reductase deficiency syndrome: A condition in which the body does not effectively convert testosterone into dihydrotestosterone, resulting in ambiguous genitalia at birth and variable physical characteristics as they age.
Klinefelter syndrome: A condition in which a person has an additional X chromosome (XXY), resulting in underdeveloped male sex organs and secondary female characteristics.
Turner syndrome: A condition in which a person has only one X chromosome (XO), resulting in underdeveloped female sex organs and short stature.
Swyer syndrome: A condition in which a person has XY chromosomes but lacks the ability to develop male sex organs or hormone production, resulting in underdeveloped female sex organs.
Mixed gonadal dysgenesis: A condition in which a person has both male and female reproductive tissue present in their gonads, resulting in ambiguous genitalia and varying hormone levels.
"The number of births with ambiguous genitals is in the range of 1:4500–1:2000 (0.02%–0.05%)."
Yes, there are other conditions that involve atypical chromosomes, gonads, or hormones, but not all clinicians recognize them as intersex. The prevalence of "nondimorphic sexual development" might be as high as 1.7%, according to Anne Fausto-Sterling and co-authors.
"Some persons may be assigned and raised as a girl or boy but then identify with another gender later in life, while most continue to identify with their assigned sex."
"In the 19th and 20th centuries, some medical experts devised new nomenclature in an attempt to classify the characteristics that they had observed." Terms such as "hermaphrodites" or "congenital eunuchs" were previously used but are considered misleading and stigmatizing now.
In clinical settings, the term "disorders of sex development" (DSD) has been used since 2006.
"Intersex people face stigmatization and discrimination from birth, or following the discovery of intersex traits at stages of development such as puberty."
"Some intersex infants and children, such as those with ambiguous outer genitalia, are surgically or hormonally altered to create more socially acceptable sex characteristics."
This is considered controversial, with "no firm evidence of favorable outcomes."
"Such treatments may involve sterilization." Additionally, elite female athletes have been subjects of such treatment.
Increasingly, these issues are considered human rights abuses, as stated by international and national human rights and ethics institutions.
"In April 2015, Malta became the first country to outlaw non-consensual medical interventions to modify sex anatomy, including that of intersex people." These quotes should help provide answers to the study questions.