Intersex people are born with atypical sex characteristics. Intersex relates to a range of congenital physical traits or variations that lie between stereotypical definitions of male and female. That is, physical differences in chromosomes, genetic expression, hormonal differences, reproductive parts like the testicles, penis, vulva, clitoris, ovaries and so on. Many different forms of intersex exist; it is an umbrella term, rather than a single category.
Intersex differences usually have a manifestation in primary or secondary sexual anatomy that is visible either externally or internally. We are intersex because our innate sex characteristics seem to be either male and female at the same time or not quite male or female or neither male or female.
Intersex is not about transition, or a trans identity or experience, and nor is it about same sex attraction. Brain differences may correlate with both same sex attraction and trans gender diversity, but intersex isn’t about brain structure.
Intersex is not always immediately apparent because in our society we do not commonly look at each other’s genitals or internal organs. Intersex may be somewhat apparent in innate physical differences in secondary sexual characteristics such as muscle mass, hair distribution, breast development and stature.
The UN Office of the United Nations High Commissioner for Human Rights states, in the May 2015 Report A/HRC/29/23 on “Discrimination and violence against individuals based on their sexual orientation and gender identity”:
Many intersex children, born with atypical sex characteristics, are subjected to medically unnecessary surgery and treatment in an attempt to force their physical appearance to align with binary sex stereotypes…
An intersex person is born with sexual anatomy, reproductive organs, and/or chromosome patterns that do not fit the typical definition of male or female. This may be apparent at birth or become so later in life. An intersex person may identify as male or female or as neither. Intersex status is not about sexual orientation or gender identity: intersex people experience the same range of sexual orientations and gender identities as non-intersex people.
The Council of Europe, in a 2013 explanatory memorandum to Resolution 1952 on Children’s right to physical integrity, defined intersex as follows:
The term “intersex” refers to atypical and internal and/or external anatomical sexual characteristics, where features usually regarded as male or female may be mixed to some degree. This is a naturally occurring variation in humans and not a medical condition. It is to be distinguished from transsexuality, a phenomenon where someone has an evident sex, but feels as if he or she belongs to the other sex and is therefore ready to undergo a medical intervention altering his or her natural sex.