More men than women are incompetent/very competent
Womens’ rights campaigners are always making a big fuss about the huge impact equal rights/sex discrimination laws have had on increasing the career opportunities for very capable women to break the ‘glass ceiling’. The very capable end of the ability scale has always been sparsely populated and any significant impact is more likely to be noticeable in the less capable bands of the scale.
When I started out working in software development, if there was a women working on a team the chances were that she would be towards the very competent end of the scale (male/female ratio back then was what, 10/1?). These days, based on my limited experience, women are less likely to be competent but still a lot less likely, than men, to be completely incompetent.
Based on my experience+talking to others it would appear that women are still underrepresented at the very competent/incompetent ends of the scale in software development. Why might this be (apart from being a sample size issue)? While the average value of male/female intelligence are the same (IQ tests are constructed to make them equal), the variance in IQ between the sexes is very different. The following is taken from Population sex differences in IQ at age 11: the Scottish mental survey 1932
The above plot provides a possible explanation for the prevalence of men at the very competent/incompetent ends of the scale and suggests that women should outnumber men in the middle, competent, band.
In practice there are still far fewer women than men working in software engineering, so a comparison using absolute counts is not possible; good luck running a survey covering software developer competence.
If the above IQ distribution carries over to competencies then it seems to me that those seeking to attract more women into software engineering, and engineering in general, should be targeting the more populous middle competence band and not the high fliers. Companies make a big fuss about wanting high fliers but in practice are often willing to take on people who are likely to be competent if they are the safer choice (that guy who appeared rather unusual during the interview may turn out to be flop rather than a rock star).
You hear women complaining about the glass ceiling, but not many complain about the way the prison population is 90% male.
Since a man can potentially produce unlimited offspring (given the right circumstance and access to sufficient females) while a woman’s limitation comes from her own body and health… over millions of years of evolution, somewhat erratic and eccentric behaviour has paid off for men, but doesn’t pay off for women. Exactly which type of eccentricity will hit the big genetic payoff in a given generation is probably not something that can be inherited; it changes from year to year and place to place.