We Need to Talk About Sex Differences

The fourth excerpt from my forthcoming book, A Billion Years of Sex Differences

Nov 26, 2025

We Need to Talk About Sex Differences

Let me indulge a brief fantasy: Everyone who reads the last section agrees with every last word I wrote. In this fantasy world – this wonderful utopia – would the critics of sex differences research hang up their hats and withdraw their opposition, their concerns about the research allayed?

Probably not. Many would still worry that, even if my rebuttals are correct in principle, not everyone will get the memo, and claims about sex differences will continue to have pernicious effects. Most people will exaggerate the differences, and many will also moralize them, treating them as goals or ideals rather than mere statistical generalizations. We know they will because we know that, throughout history, people have routinely done just that. And we know as well that, throughout history, exaggerating and moralizing sex differences has had extremely harmful consequences.

You might be surprised to hear that I agree: People all too easily exaggerate and moralize sex differences, and doing so produces many harms. It creates social pressure to conform to exaggerated stereotypes of the sexes, and intolerance of those who don’t: stay-at-home dads, women who put career before kids, and other gender rebels. It leads us to discriminate against women and against men, treating them not as individuals but as instantiations of the statistical properties of their sex. It leads us to overlook or stigmatize gender-atypical problems, such as ADHD, autism, and drug abuse in females, and depression, eating disorders, and sexual victimization in males. And it leads us to underestimate the extent to which gender gaps in society are still shaped by bias and barriers, thus failing to identify remaining injustices that could otherwise be dismantled.

Given these very real harms, the question many people have is this: What the hell are we doing? Why would we want to risk talking about and researching sex differences?

It’s a good question, but I think I’ve got a good answer. In fact, I’ve got two. The first is that even though the risks are real, the sexes do differ on average, and we can’t just lie about that. What we should do instead is tell the truth carefully. We should emphasize at every turn that the gaps are generally modest, that they’re rarely set in stone, and that they’re statistical trends, not life goals or moral imperatives.

My second answer is that exaggerating and moralizing sex differences isn’t the only mistake on the menu, and isn’t the only mistake that causes harm. Minimizing and denying sex differences – or moralizing the absence of sex differences – can cause various harms as well. It creates social pressure to reject traditional gender roles, effectively replacing one gender straitjacket with an equally restrictive unisex or gender-role-reversed one. It leads to failures of cross-sex mindreading that create unforced errors in our dating lives, family lives, and work lives. It leads us to overlook physical and mental health problems that manifest differently in one sex than the other, including heart attacks, autism, and ADHD in females, and depression and anxiety in males. It leads to misguided practices such as testing drugs on men only, thereby potentially putting women’s lives at risk. It hobbles our ability to solve our most pressing social problems by blunting our understanding of the true causes of those problems; as policymakers like to say: Wrong diagnosis, wrong cure. And it leads us to overestimate the role of gender bias in shaping the modern world, with downstream harms such as pouring time and money into interventions that don’t work, pressuring people to make life choices that don’t mesh well with their preferences, and inadvertently reversing the direction of discrimination rather than eliminating discrimination altogether.

With dangers of erring in either direction, how can we navigate a safe passage through the minefield? I hope the answer is obvious. We have no responsible choice but to take a Goldilocks approach to the issue, striving to walk the thin pink-and-blue line between exaggerating and minimizing sex differences: the alpha bias and the beta. Once again, if we want to make the world a better place, our best bet is to ensure that our picture of the world is accurate.

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