If women are so equal, why aren’t there more of us in science and, for that matter, in politics? On the 100th anniversary of International Women’s Day, I got an earful about this stuff. The gender lopsidedness in certain fields obviously proves that, despite women’s impressive gains, we still have a long way to go before we can declare victory in the battle for women’s rights.

The trouble is, it’s not at all obvious why these gaps persist, or what should be done about them. The hackneyed old complaints about systemic bias against women no longer seem convincing. Yet, other hypotheses can be downright dangerous. Just ask Larry Summers, the former Harvard president who was ultimately ousted after he speculated that the preponderance of men atop certain math-heavy fields might partly be explained by the higher variance of male IQ scores at the extreme top and bottom of the Bell curve. Kapow! Instead of defending his right to think freely, academics demanded his head.

But now, Stephen Ceci and Wendy Williams argue that it’s time to change the conversation. As academics at Cornell University – they’re married to each other – they’ve been studying the science gender gap for years. And they’ve concluded that the last thing we need is more gender sensitivity training. In a new paper published in the Proceedings of the National Academy of Sciences, they say the bias alleged against women in science simply doesn’t exist. The scientific gender gap is largely due to different job choices.

“We often hear that men have a better chance of getting their work accepted or funded, or of getting jobs, because they’re men,” Prof. Williams says. But they found no evidence of systemic bias in interviewing, hiring, reviewing or funding. If anything, female PhDs had a modest hiring edge. “Universities expend money and time trying to combat this rampant alleged discrimination,” she says. But, in her view, they’re wasting their time and money.

Yet, certain barriers remain, and they’re real. The principal barrier is the same one that other professional women face. A scientist’s prime reproductive years coincide with her prime research years. Female scientists often take more junior positions not because their manuscripts were rejected but because they choose to give priority to their families. About 80 per cent of both male and female graduate students believe that working full-time is “important” or “extremely important.” But nearly a third of women (against just 9 per cent of men) also believe that working part-time is “important” or “somewhat important.”

Family considerations aren’t the only reason women make different career choices than men do. Women tend to prefer jobs that involve interacting with people rather than with data. Many would rather teach than do pure research. And far more women gravitate to the “human” side of sciences (medicine and the biological sciences) than to the math-intensive side (computer sciences, engineering, physics). These preferences may be a result of cultural stereotyping, but they also seem hard-wired. Should we be equally alarmed that women now outnumber men by 3 to 1 in veterinary school? Maybe not.

Prof. Williams, who has three daughters, advocates doing more. She wants to ensure that girls are encouraged to go into science and are exposed to plenty of positive role models. She wants the tenure system tweaked to make it more family friendly. But she also says we should stop trying to figure out the “right” career path for women in science, and start asking how happy female scientists are with their choices.

In other words, it’s a lot more complicated than blaming men, or stereotypes, or culture, or tradition. Why don’t more women go into politics? I can think of lots of reasons, not including sexism or systemic bias. How about the excruciating difficulty of combining family life with a political career, especially if your family is a thousand miles away? What can we do about that? I don’t have a clue. All I know is, the answers aren’t as easy as we like to think.