Dating book authors and policymakers alike often claim that scientific research proves men and women are vastly different. But a team of researchers analyzed data from thousands of people across many different studies, and found that lots of traits we tend to think of as deeply gendered really aren't.
Study authors Bobbi Carothers and Harry Reis used both their own questionnaires and research by others to look at the characteristics of 13,301 men and women. Specifically, they wanted to find out whether traits like assertiveness broke down neatly by gender or were more evenly distributed, with some men and some women reporting high levels of assertiveness. Other traits they looked at included physical strength, caring for others, and being comfortable with casual sex.
The graphs above show what they found. The top one shows the distribution for physical strength — it broke down pretty cleanly along gender lines. Women were clustered at the weaker end of the spectrum, men at the stronger (though there were some weak men and strong women). This was also true of basic physical measurements like height.
But the bottom graph, of assertiveness, tells a very different story. There were more very assertive men than very assertive women, but in general men and women were quite spread out across the assertiveness spectrum. While strength broke down cleanly along gender lines, assertiveness was more of a continuum. Just knowing that someone was highly assertive wouldn't reliably indicate whether they were male or female.
The same was true of the following traits:
• desire to have sex with multiple partners
• frequency of masturbation
• willingness to have sex outside of a relationship
• empathy for others
• caring about close relationships
• closeness with a best friend
• fear of being too successful (as measured by agreement with statements like "Often the cost of success is greater than the reward")
• interest in science
Essentially all of the personality traits that the researchers looked at followed a pattern like the assertiveness graph. Men may be somewhat more likely than women to possess some of these traits, and vice versa, but none of them look like the strength graph, with men clearly at one end and women clearly at the other. None of the traits are exclusively male or female — if, for instance, you knew that someone wanted to have sex with a lot of people, you couldn't determine with statistical accuracy whether that person was a man or a woman.
"There are not two distinct genders," the study authors write, "but instead there are linear gradations of variables associated with sex, such as masculinity or intimacy [...] Thus, it will be important to think of these variables as continuous dimensions that people possess to some extent, and that may be related to sex, among whatever other predictors there may be."
So while gender may be one factor influencing whether someone is assertive, likes science, or wants to have casual sex, it's far from the only one.