Intersex is an umbrella term that describes bodies that fall outside the strict male/female binary. There are lots of ways someone can be intersex.
Intersex is a general term used for a variety of situations in which a person is born with reproductive or sexual anatomy that doesn’t fit the boxes of “female” or “male.” Sometimes doctors do surgeries on intersex babies and children to make their bodies fit binary ideas of “male” or “female”. Doctors always assign intersex babies a legal sex (male or female, in most states), but, just like with non-intersex people, that doesn’t mean that’s the gender identity they’ll grow up to have. This brings up questions about whether or not it’s acceptable to do medical procedures on children’s bodies when it’s not needed for their health.
Miriam van der Haave gives us another perspective: “Intersex refers to the lived experience of the socio-cultural consequences of being born with a body that does not fit within the normative definitions of "man" and "woman." In short, it is about our experiences and not a medical diagnosis.”
The fact that a person has an intersex body can become apparent at birth, in early childhood, in puberty, or even in adulthood. A study Living with intersex/DSD: An exploratory study of the social situation of persons with intersex/DSD published in the Netherlands in 2014 reveals that at least 1 in 200 intersex people are at risk of being subjected to invasive surgeries and other medical interventions, e.g. hormonal treatment, based on being diagnosed by medical professionals as having a “Disorder of Sex Development” (DSD) or an unspecified diagnosis, such as “unspecified malformation of the male/female genitalia”
“Disorder of Sex Developmen” (DSD) is a medical umbrella term, which was introduced in 2006 by a Clinician Consensus Statement. It replaced the older terms used for intersex people, the oldest one of which was “hermaphrodite”. Some clinicians use DSD to stand for “differences of” or “diverse” sex development. In any of its forms, the term DSD pathologizes healthy variations of sex characteristics and refers to intersex sex characteristics as characteristics that are “deviant” from the norm of male and female bodies, and thus need to be “fixed”. By implying the necessity of “normalizing” therapies for intersex individuals, the term DSD breaches human rights standards.
https://www.nhs.uk/conditions/differences-in-sex-development/
How many people are intersex?
United Nations Office of the High Commissioner for Human Rights (2015): Fact Sheet. Intersex
Intersex people are often thought to be a rare find, however, according to the United Nations up to 1.7% of the population, or, globally speaking, as of 2020 over 131 million people have been born with intersex traits.