We’ve been debating the gender pay gap in Economics A-level over the past few weeks. In particular, students are asked to consider the case for government intervention on this issue. To do that, you have to look at the causes of the gap. We looked at such issues as sexism and childbearing, but for not enough time, I now realise, at a major reason for the current pay gap..the choices girls make for the subjects they study at school.

I saw some statistics the other day provided by Emma Duncan in the a Times that made me sit up and take notice of this in a big way. Given I am in the position of advising students on their GCSE, A-level and University choices, I am aware that I can see, and do something about a major cause of the gender pay gap. But, as with many things, there is only so much I can do.

Duncan wrote her article in response to some legislation suggested by Labour MP Sarah Champion, who wants to make the FTSE 250 companies publish their own gender pay gaps. Duncan could see that this legislation would simply reveal the symptoms, not address the causes.

A simple explanation would be sexism, and it was certainly true in the past that women were paid less than men for the same job. But the Equal Pay Act and quick-on-the-draw lawyers and employees have made that more or less impossible now.

A more complex explanation is childbearing. The time off that women take to bear children takes them off the professional ladder, and then they are less likely to be happy to do the things like foreign trips required to get them back on it when their children are young. This is why the gender pay gap increases so much once women are in their thirties. Government policies like shared parental leave and company programmes like flexible working can only make marginal inroads into this problem. What is needed is for men to step up and share the burden properly. If all couples who have children share parental leave equally it would make a massive difference to the gender pay gap.

But consider this: the two great boom industries over the past 25 years have been in technology and finance. Fortunes have been made, but in almost every single case not by women. It is the reason why the gender pay gap has come down to about 10% for median wage jobs but for the top 10% of paid jobs it is stubbornly staying at over 20%. The key jobs, in terms of the ones that make most money in technology and finance are developing software and taking large financial bets. Some say that women don’t like the long hours and testosterone fuelled atmosphere of financial dealing rooms, others say that girls just don’t like to code. I say that both can be dealt with. You reduce the testosterone in a financial dealing room by, literally, reducing the testosterone. As for the coding, well, you can’t like to code unless you learn to code.

But over 90% of A level computing students are boys. The most boy-heavy A level subjects after that are Maths, Physics and Economics, all of which contribute to careers in finance. The most girl-heavy A level subjects in the UK are Drama, Sociology, Art and Welsh. Just think about the differences in opportunities for earning between students who do those two sets of A level programmes. When PISA do their study comparing educational ability between countries, the greatest gap between girls and boys for Maths and Science in the whole of Europe is in the UK. China has no gender gap here at all.

There are things that our Government can do to close this gender gap in science and maths, and some of them are being done right now. All pupils should be taught coding in Primary school, and we need to set aside money to deal with the shortage of Physics teachers. The government could also set targets, with additional funding attached, for schools to get girls studying Computing, Maths, Economics and Physics. These solutions, Duncan points out, wouldn’t just close the gender gap, they would address the shortages in computing and engineering skills that are affecting the competitiveness and productivity of our industrial sectors.

But ultimately, there is only so much you can do. Girls need to want to study these subjects. Girls’ parents need to want their daughters to study these subjects too. Duncan presents a final fact that each Science or Maths A-level studied at A-Level raises someone’s earnings by the age of 30 by around 10% each. This means that if girls want to catch up with boys on pay, they need to learn to love equations. But it’s all very well knowing that, the next step is in our girls’ hands.

But