Sexual Diversity, “Biological Sex,” and Intersex

As a scientific classification, humans are sexually dimorphic, meaning that we are split up into a gender binary, assigning those born with external genitalia “male” and those with internal genitalia “female.” To this extent, we have a common rhetoric that “biological sex” regards the genitalia and chromosomal makeup of an individual.

However, this model is slightly inaccurate and missing a lot of common variation among humans.

Humans were believed to be strictly born as having external genitalia or internal genitalia, but there can be a combination, or even a different expression that isn’t entirely one or the other.

This can also occur with the genetic makeup of humans. Chromosomally, males are classically XY and females are XX. This is because on the Y chromosome, there is a coding region called “sex-determining region Y.” If this coding region is present in a genetic combination XY, it triggers a hormonal cascade that eventually develops the fetus into a male, and without it, the fetus will develop into a female. In a classic XX combination, there is x-inactivation, and one X chromosome is inactivated, allowing for genetic variance among offspring.

However, there are many mutations that may occur, including but not limited to: XXY, XO, XYY, and so on. Those that are non-fatal mutations may lead to variation in phenotypic expression, especially in the gonads and genitalia.

These variations are referred to as “Intersex,” meaning that their sex does not strictly fit male or female. Due to this, the term biological sex is considered outdated, and often can be offensive when used to refer to transgender individuals. This is especially true because the context in which it is used often reflects the desire to know what genitalia someone has, and as that is very personal, is an invasion of privacy.

For more information regarding intersex, please visit The Intersex Society of North America‘s website.