Debunking the Pop Psychology View of Gender/Sex

There is no such thing as "femaleness" vs. "maleness" according to a recent article in the APA Journal American Psychologist. This is a summary of that article. But don't all mammals come in males and females, with different roles in reproduction? And aren't humans mammals, with women the females of the species, and men the males? Reproductive organs and genitalia typically come in two patterns: ovaries, uterus, vulva etc. for females; testes, prostate, penis etc. for males. But gender, masculinity and femininity, are for the most part cultural constructs, like race and nationality, with little basis in biological or psychological facts.

There are no "female brains" or "male brains" only human brains. Popular research shows evidence of brain differences between men and women. In a recent study of 1400 human brains, Joel and colleagues looked at how internally consistent these differences were. They divided the 1400 brains into thirds, the 467 "most female" brains, the 467 "most male" brains, and the 466 in the middle, according each of 7-12 features that showed the largest differences between males and females. They found that the biggest proportion of brains (23-53%) were "most female" for some things, and "most male" for other things. Only 1-10% were consistently "most female" or "most male" depending on which measures they looked at. The rest were "most female" or "most male" on some things, and in the middle on others, or consistently in the middle. By contrast, reproductive organs and genitalia are dimorphic, occurring in two distinct forms, with around 98% of people having either the male typical pattern, or the female typical pattern. Human brains are not dimorphic.

Sex hormones are about the same in men and women, and respond to behavior more than causing it. Sex hormones such as estrogens (eg. estradiol) and androgens (eg. testosterone) cause the differentiation of male and female genitals during a specific phase of prenatal development. But the rest of the time, the levels of these hormones are similar in males and females. Levels of progesterone and estradiol are about the same in men and women, except for pregnant women. Testosterone increases in males and females around puberty, more so in males, but there is considerable overlap. Levels of testosterone are inheritable, so if your parents had high testosterone you are likely to as well. Testosterone responds to behavior. For example, Van Anders showed in a series of studies that sexual thoughts increase testosterone in women, whereas nurturant parenting behaviors decrease testosterone in men. Decreases in testosterone in men during their partners' pregnancies predict parenting behaviors. Progesterone and estradiol vary over women's reproductive cycles, but also increase in response to engaging in dominance contests, social closeness and social rejection.

Gender stereotypes are inaccurate. Joel and colleagues looked at 10 highly stereotyped behaviors in US college students - boxing, construction, playing golf, playing video games, scrapbooking, taking a bath, talking on the phone, watching porn, watching talk shows, and using cosmetics. They defined "feminine" and "masculine" cutoff scores as the scores of the most extreme 33% of women and men, respectively. Over 55% of students showed some mix of "feminine" and "masculine" behaviors, whereas fewer than 1% endorsed only "feminine" or only "masculine" behaviors.

We have gender-based stereotypes about a lot of psychological traits, for example mathematical ability, depression and sexuality. These stereotypes are at best inaccurate and often also wrong. Meta-analysis, research that summarizes data from many published studies, shows that these differences, where they exist, are smaller than we think. Most males and females are similar, with a few extremes. Most people are in the overlap, even with a moderate difference between the "average" male and the "average" female. The graph above illustrates distributions of "males" (blue dots) and "females" (pink dots) on some trait where the difference between them is considered "medium" as measured by d = 0.5.

So what about math performance? In US children from grade 2 through 11, d ranged from -0.02 to 0.06, indicating no gender difference. As for sexuality, many attitudes and behaviors were about the same (d around or less than 0.1) in males and females surveyed. For example same-gender sexual experience and attitudes about homosexuality. Age at first sex, attitudes about sexual permissiveness and attitudes about masturbation were slightly different (d around 0.2). Larger differences (d around 0.5) were found for use of pornography, masturbation, and attitudes about casual sex. But a glance at the graph above shows that even with d = 0.5 by far the majority of people (dots in the graph) are in the region of overlap. These larger differences varied by country and were smaller in nations where women were more empowered. Depression? About 3 times as many teenage girls are depressed as compared with teenage boys, which is d = 0.6. Before age 12 and after age 20 around twice as many females are depressed, d = 0.4. I'm curious if this difference also varies with women's empowerment.

It's important to remember that nearly all the research included in these meta-analysis surveys was aimed at finding differences between males and females, and indeed claimed to show such differences. Even so, what they actually found was that males and females are mostly similar, with some small differences on average if you sample enough people. Hyde (2005) called this the "gender similarities hypothesis." Based on 124 published psychological gender difference studies, 30% were trivial (d around or less than 0.1), and 48% were small (d around 0.2), so a full 78% of gender difference studies actually show gender similarities! (If you're confused by the math, this is an "emperor has 78% no clothes" kind of statement).

Transgender and nonbinary individuals are often excluded from studies about gender. But what can we learn from them about the development of gender identity? Studies show that trans girls behave just like cis girls, and trans boys behave just like cis boys, and not according to their sex assigned at birth. Children in general learn gender stereotyping rapidly because we do such frequent and elaborate displays of gender, by adopting different roles, different clothing, and even using language differently for males and females. Nonbinary individuals either don't categorize themselves as male or female, or identify as gender fluid, changing gender over time. In a survey of men and women, asked if they thought of themselves in the past 12 months as "always," "often," "sometimes," "rarely" or "never" as "a man" or "a woman" 35% of respondents felt to some extent like the other gender. So while transgender and nonbinary individuals are a small minority, many people can relate to their experiences.

Why does this matter? Gender discrimination is based on faulty stereotypes. People outside the gender binary are denied the right to self-determination of their gender/sex, including the right to choose an identity outside the gender binary. Children grow up with harmful stereotypes about their own and others' abilities and dispositions. Ignorance about hormones led to women athletes being banned for "hyperandrogenicity" despite no evidence in 2006, a decision that was struck down in 2015 by the international Court of Arbitration for Sport but only after many women athletes were invasively scrutinized.

What can we do about it? The authors of the article suggest that "the gender binary should be replaced by a conception of gender/sex that stresses multiplicity and diversity" rather than a binary system of "male" and "female." The new system would include categories that are not mutually exclusive, can vary over time, and allow for the possibility of opting out of gender altogether.