Sexual Characteristics: Understanding Biological Diversity

What are Sexual Characteristics?

When we talk about “sex,” most people immediately think of external genitalia. But biological reality is a much richer and more complex tapestry. Sexual characteristics refer to all the traits that biologically differentiate bodies, and this list is much longer than one might imagine.

Primary and Secondary Sexual Characteristics

First, we distinguish what are called primary characteristics, those you are born with. These include your chromosomes (the famous XX or XY pair, which also has many other variations), your gonads (ovaries or testicles) that produce hormones, your internal reproductive organs, and your external genitalia (penis, scrotum, clitoris, vulva).

Then come secondary sexual characteristics, which appear mainly at puberty, under the effect of hormones. This is everything that shapes your appearance: breast development, facial and body hair, voice change, skeletal shape, fat distribution (more on hips and thighs, or on the abdomen), skin texture, or jaw shape.

Sex: A Complex Spectrum

This fragmented view clearly shows that “biological sex” is not a simple binary box. It is a spectrum, a continuum of characteristics.

Sexual Characteristics and Gender Transition

For trans people undergoing a medical gender transition, the goal is precisely to act on some of these characteristics, mainly secondary ones via hormones and sometimes primary ones via surgery, to bring their body into harmony with their gender identity.