One of the most frequent discussion topics I encounter at defence industry conferences is the STEM-qualified workforce problem.

BAE Systems Australia CTO Brad Yelland illustrated it best at the National Defence Industry Skilling and Workforce Summit in Perth a few weeks ago.

“In [the next three years], Australian universities will graduate about 34,000 engineers. That may seem like a lot, but of those, only around 25 per cent are eligible to work in defence industry,” Yelland said. “That’s about 8500 people.

“Let’s be optimistic and say that half of those actually want to work in defence industry,” he continued. “We’re now down to around 4000 engineers. BAE Systems Australia needs a third of those, so I don’t know what the rest of you are going to do.”

One of the most frequent answers to this problem is to diversify the workforce. According to ADM Top 40 survey data, defence industry reports average female workforce participation at 24 per cent, which is about half the national average (47 per cent). That looks like ample room to recruit more STEM-qualified women into defence industry. Moves to invest in girls’ STEM education and improve gender equality at a national level should help – right?

Not quite. According to a paper published last year in Psychological Science, women make up about 24 per cent of STEM graduates in Australia, a similar level to Ireland, Sweden, Spain and Switzerland. Yet women make up 41 per cent of STEM graduates in Algeria, 38 per cent in Tunisia, 37 per cent in the UAE and 36 per cent in Turkey. The paper reports a paradox; more gender equality means fewer women in STEM.

To be clear, the paradox isn’t the product of capability. The survey covered 475,000 students across 67 countries and found that boys and girls show similar levels of science literacy globally. In Finland, a country with a high level of gender equality, girls show more science literacy than boys. Yet Finland has one of the largest STEM gender gaps in the world, just ahead of Norway and Sweden.

Instead, the paradox is the product of each individual’s own academic strengths. Boys and girls are equally competent at science worldwide, but girls tend to be even better at other subjects, whereas boys tend to be stronger in science than they are elsewhere. In other words, a girl who is good at science and maths will likely be even better at reading: a boy who is good at science and maths is less likely to be better at reading. She is more likely to identify reading as her strength whereas he is more likely to stick with science. She goes on to study humanities; he goes on to become an engineer.

Women in less equal countries don’t have that choice. They might be even better at reading, but STEM fields pay much more and so more girls choose that path. The cycle may also be self-reinforcing – as more girls choose STEM, perceived barriers to participation lower.

As Olga Khazan wrote in the Atlantic: “It’s not that gender equality discourages girls from pursuing science. It’s that it allows them not to if they’re not interested.”

So what does this matter? Well, it means that improving science education for girls and wider gender equality won’t solve the STEM-qualified workforce problem. Efforts to get more women into STEM, and especially into defence industry, need a more personalised understanding of individual academic strengths.

In a more equal society, girls who are excellent at STEM but even better at other things won’t choose defence industry simply because it pays well and there’s plenty of opportunities. They’ll only choose it if they find it more interesting than all their other options. This message is critical for defence industry to understand if it wants to actually solve the workforce problem.