The idea of gender is undergoing a revolution, as unconventional gender behaviors gain in acceptance. At the same time, however, virtually every societal move away from the gender binary—such as permitting gender-neutral designations on various documents—triggers a corresponding backlash.

These controversies bring to the fore a centuries-old question: how fundamental are sex categories? Do humans “naturally” belong to one of two groups, female or male, that are distinct not only in the form of their genitals but also in their brains and behavior?

For about 1 percent of humans, answering this question in the affirmative leads to a great deal of physical and emotional pain. These are people born with intersex genitals; for them, being forced to fit into one of two sex categories often means facing ostracism or undergoing medically unnecessary surgeries. But what about all the others? Do humans with female and male genitals belong to two distinct classes?

Studies comparing groups of women and men often find differences between the two. Some of these are small (for example, women’s reading comprehension is, on average, slightly better than men’s); other differences are large (for example, most women prefer a man as a sex partner whereas most men prefer a woman). One can argue ad infinitum as to whether these differences stem directly from an individual’s sex (for example, a result of exposure to high levels of testosterone in the womb), or from the different ways in which society treats individuals with female and male genitals. But this nature-versus-nurture debate is irrelevant to the question: do women and men belong to two distinct classes?

If so, then characteristics on which women and men differ should add up consistently within each individual—just as genital organs do (most humans have genital organs that are either all male or all female; only that 1 percent with intersex genitals have a mixture of the two types). But differences in brain and behavior between men and women don’t add up in this manner. Very few individuals have only female-typical or only male-typical characteristics. Most humans are a mixture of both—a unique mosaic of female-typical and male-typical characteristics. Our scores on various neural, psychological and behavioral parameters don’t consistently add up in any one person. Rather, they mix up. You may very well score high on the ability to visualize geometrical objects, as is more common in men, but at the same time, you may be more interested in people than in things, as is more common in women. You may be a nurturing type and also good at fixing things. The list of potential mosaics goes on and on.

But if humans are mosaics of features, why do men and women sometimes seem to be so distinct? The answer lies in the binary division itself. Even though humans do not belong to two distinct sets in terms of their brains and behavior, the binary division of humans into two social categories is real, and it exerts a profound effect on the way we behave and the way we perceive ourselves and others. The gender binary assigns different roles, status and power to humans with male and female genitals, and different expectations from them in terms of their behaviors, preferences and psychological characteristics; it forces a population of human mosaics into a binary straitjacket.

Some of the effects of this role assignment may be relatively benign—discouraging people from baking cookies or mastering other skills they might consider “gender-inappropriate.” But many are not: Even in gender-aware Western societies, the binary affects women’s and men’s career choices; exposes women to gender and sexual harassment; and leaves men to die in droves in armed conflicts and in work-related accidents.

It is time to get rid of the gender binary. It is time to start treating people according to their unique mosaics of characteristics rather than according to the form of their genitals. It is time for a world with no gender.

A world with no gender means that the form of one’s genitals, whether female, male or intersex, has no social meaning—just as being right- or left-handed has no inherent meaning. (Although it used to: not so long ago, left-handed people were considered less capable than those who are right-handed, and parents would force their left-handed children to use the right.

It’s no coincidence that “right” is another word for “correct.” Scientists, meanwhile, searched for the neural deficits responsible for left-handedness. All these efforts have vanished, even though we are still left- or right-handed, and even though left-handed people are often frustrated that many tools and other objects are designed only for righties.

A world without gender does not mean there would be no differences, on a group level, between humans with female and male genitals. But in a world without gender, we simply wouldn’t care. And why should we? If your child excels in math, or if you love poetry, does it really matter whether there are more people with female or male genitals among math wizards or poetry buffs?

I’ve had people tell me that the gender binary is a direct consequence of there being two sex categories. But even if this were true, it would provide an even stronger argument for getting rid of the binary gender system. Because if the effects of sex are unavoidable, then there is surely no need for a complex social system to enforce them

A world without gender is a world in which humans are encouraged to develop their full human potential. It’s a world in which characteristics that are considered desirable for humans, such as empathy and assertiveness, are encouraged in everyone, regardless of the form of their genitals—and regardless of whether they have difficulties in acquiring these characteristics because of their genes, hormones, inadequate parental treatment, or socioeconomic conditions. At the same time, children and adults possessing characteristics that are considered undesirable, such as aggressiveness, are helped in overcoming them, regardless of their cause.

A world without gender is a world in which humans are free to fully express their talents in all areas, be it math, poetry—or both; in which humans are treated according to who they are, and not according to the form of their genitals; in which even the thought of grouping them by their genitals sounds as bizarre as grouping people according to the color of their eyes.