Are there only two genders?

Few topics are discussed with more feeling than gender. The question can sound simple, but the answer depends heavily on what the words mean. People often use "sex" and "gender" for different things, or for the same thing, and much of the disagreement comes from that.

In biology, sex usually refers to physical traits such as chromosomes, hormones and anatomy. Most people are male or female, and many biologists describe sex in humans as two categories, based on the type of gamete a body is organised to produce. A small share of people are born with variations in sex characteristics, which are sometimes called intersex, and people disagree about whether this means that sex is better described as a spectrum [check: use a reputable source for the figures if you cite any].

Gender, in many fields, refers to the social and psychological side: roles, expectations, and a person's inner sense of who they are. On this view, gender identity can differ from the sex a person was assigned at birth, and societies in many places and times have recognised more than two categories, such as the hijra in South Asia or two-spirit people in some Indigenous North American cultures.

People who say there are only two genders usually argue that gender follows biological sex, that male and female are the basic categories of human biology, and that changing definitions causes confusion in law, sport, medicine and language. People who say there are more than two argue that identity is real and varied, that rigid categories exclude and harm people who do not fit them, and that language and law should reflect how people understand themselves.

Many people hold views in between, for example that sex is binary but gender expression is varied, or that definitions should depend on the context. Laws and policies differ between countries.

If you take part in this debate, it helps to define your terms first, to treat people with respect, and to keep to what you can support.