When she was fifteen, my grandmother begged her parents for permission to stay on at school. Sadly, they didn’t see the point. In the minds of many people at the time, academic education wasn’t ‘for’ working class children – and especially not working class girls.

In the last house she lived in, there’s a still a room full of the history books that she loved, but never had the chance to study in a formal way. Seeing them today reminds me not only of her life, but also the stolen potential of so many other lives.

The weight of all those years of prejudice is such that we often assume that girls, more than boys, are held back by the failings of the education system. This is true in some parts of the world – but it is no longer true of the developed world.

In a balanced and insightful piece for the New York Times, Eduardo Porter looks at the latest evidence:

“Last week the Organization for Economic Cooperation and Development — a collective think tank of the world’s industrialized nations — published a report about gender inequality in education, based on the latest edition of its PISA standardized tests taken by 15-year-olds around the world.”

In a few subjects, boys do still have the advantage:

“Top-performing boys score higher in math than the best-performing girls in all but two of the 63 countries in which the tests were given…”

Overall, however, it’s the boys who lag behind – especially among the least advantaged pupils:

“Six out of 10 underachievers in the O.E.C.D. — who fail to meet the baseline standard of proficiency across the tests in math, reading and science — are boys. That includes 15 percent of American boys, compared with only 9 percent of girls. More boys than girls underperform in every country tested except Luxembourg and Liechtenstein.”

The disparity is particularly pronounced on the most important metric – reading ability:

“At the bottom, the gap is enormous: The worst-performing American girls — who did worse in reading tests than 94 out of every 100 of their peers — scored 49 points more than bottom-ranked boys, a 15 percent gap. And the deficit across the O.E.C.D. was even bigger.”

If this imbalance had been the other way, you can be sure there’d be a great deal more attention paid to it. Almost certainly, it would be ascribed to continuing patterns of prejudice against female education.

It may be that some of the old discrimination does still persist – but, if so, that makes the comparatively poor performance of boys all the more remarkable. So, what explains it?

Could it be that the receding tide of chauvinism is exposing male weaknesses that were always there – such as a tendency to indiscipline, lack of concentration and disengagement from academic study?

Could it also be that family breakdown and the absence of positive role models is exacerbating these factors? Eduardo Porter notes that the OECD evidence “meshes with findings that American boys from poor, single-mother families tend to do worse than girls.”

If this is a big part of the explanation, then getting policy makers to take action will be difficult. Social policy is dominated by the assumption that all problems are caused by prejudice and inequality. The impact of family breakdown is, of course, far from equal – hurting the poor much more than the rich. But, unfortunately, this is one kind of inequality that our politicians would rather not talk about.