Variety in our bodies

How many times have you filled out a form at the doctor’s office and checked a box for “male” or “female”? Pretty simple, right? Except there’s more to biological sex than meets the eye. Researchers are learning that there is tremendous variety in human bodies, including differences among males and females.

Long story short, primary sex characteristics (body parts directly related to reproduction) + secondary sex characteristics (features that develop during puberty) combine in a lot of different ways. Human beings are incredibly diverse, and that variety extends to characteristics such as our tone of voice and whether our facial features are angular or round, as well as other differences in our bodies, such as big or small muscles, large or small breasts, or hips that are narrow or wide.

The variety in our bodies also includes people who are intersex, meaning they have physical characteristics that don’t fit typical definitions of either sex. Nature journalist Claire Ainsworth (2015) explains, “[D]octors have long known that some people straddle the boundary [between male and female]— their sex chromosomes say one thing, but their gonads (ovaries or testes) or sexual anatomy say another” (Ainsworth, 2015, para. 3). There are a wide range of intersex variations, including some that are visible at birth and others that become evident during puberty.

Featured Content

Read this Q&A from the American Psychological Association to learn more about the different kinds of intersex traits.

Answers to your questions about individuals with intersex conditions


Ainsworth, C. (2015). Sex redefined: The idea of two sexes is simplistic. Biologists now think there is a wider spectrum than that. Nature, 518,288-291.!/menu/main/topColumns/topLeftColumn/pdf/518288a.pdf

APA Task Force on Gender Identity, Gender Variance, and Intersex Conditions (2006). Answers to your questions about individuals with intersex conditions [Pamphlet]. American Psychological Association.

Gender Identity Gender identity icon Our core sense of who we are as a man, a woman, a mixture of both, or neither.

Gender Expression Gender expression icon How we show up in the world through choices like clothing, hair style, mannerisms or tone of voice.

Attraction attraction icon How we feel toward others sexually, romantically and/or emotionally.

Biological Sex Biological sex icon Physical attributes such as reproductive organs and genitalia, chromosomes, genes and hormone levels.

Subscribe to our monthly newsletter to gather insights and real learnings

* indicates required
Privacy Policy *