Let us thank Harvard President Lawrence H. Summers for this: He has ignited debate on an inequity that is ignored outside the academy and by many men.

Summers last month addressed the paucity of women in engineering and the sciences — he might have added his own field, economics — suggesting that the gap may be due to innate gender differences. Summers, known for his candor and provocative statements, sparked a hailstorm of criticism and swiftly issued several apologies.

When I first heard about Summers’ comments, I did the first thing that came to mind: I called his mother. Anita Summers is a Wharton professor emeritus, an authority on urban economic development, who I assume is good at math.

“Indeed, I am,” she said, and quickly defended her son. “There are a lot of areas that need to be looked at scientifically, and we need to explore those differences.”

There are inequities between the sexes in many fields, especially in the upper ranks. Whether this comes from nature or, I suspect, a profound lack of nurturing, the problem is systemic.

Like athletes, professionals succeed not only due to inherent ability but also to drive, passion and encouragement. Whenever a woman reaches the inner sanctum of the boardroom, lab or ivory tower, my first response is to ask: Did she play by boy rules or girl rules?

Boy rules mean 80-hour work weeks, being at the beck and call of superiors, forsaking motherhood and sometimes marriage, or finding a less ambitious partner willing to adjust to your needs. That is, a wife. Barring that, hiring a phalanx of excellent baby-sitters.

Girl rules mean leaving work on time for children, possibly placing career on the back burner to that of her husband, while hoping her talents will still be recognized.

Condoleezza Rice follows boy rules; Hillary Clinton, girl.

When I was in school, the renowned economics department was a bastion of men. My desire to study was considerable, though my talent was limited. Encouragement, as for many women, was nonexistent.

Though I’m not proud of this, I capitulated quickly and studied history. My goal was to thrive, to enjoy my time at the university, and not spend those years fighting men who had no interest in encouraging me.

I followed girl rules because they were natural, that is to say, easier. I had no interest in fighting life uphill. Consequently, I don’t know if playing by boy rules would have proved more stimulating and rewarding.

I’m not alone in following girl rules. Many years later, economics is still utterly dominated by men at the top, as are many of the sciences. Girl and boy divisions remain ubiquitous.

In many professions, men and single women readily sign up for tough assignments that involve extensive travel or long hours. Mothers free to do so have spouses who work at home or nurse less ambition or, again, employ a phalanx of excellent baby-sitters. These women are rarities in my generation.

I’d rather have discourse, even a battle royal, than keep thinking everything’s fine. Discrepancies between the genders aren’t due to lack of talent, only lack of opportunity and a need to rethink old models.

Karen Heller is a columnist for Philadelphia Inquirer. Her e-mail address is kheller@phillynews.com.