Although female programmers are rare now, that wasn't the case in the 70's. That shift is another argument against the natural balance hypothesis.
I am too young to know, but is this the experience of others as well?
Again, this is based purely on anecdotal experience, but I wonder if women programmers tend to concentrate into particular industries (for whatever reason). My wife was a programmer at a contractor for a large government agency, and it struck me that there was a higher concentration of women there than in other industries or in the start-up scene.
If this is generally the case, I am not sure to what extent this would support any given hypothesis.
Back in the day I think the popular perception of programmers was kind of an extension of a secretary (it's just typing on toggle panels instead of a typewriter, right?) so there were lots of women stuck in secretarial positions who tried it out.
...and those secretaries were good at it. And so were the women math PhDs who could not get jobs elsewhere. And so were the women who had female mentors, and therefore failed to be chased away. All of which dumps water on the "innate abilities" trope that people keep bringing up as the null hypothesis which must be disproved, instead of the claim which requires proof.
It genuinely weirds me out how many white males in tech see no conflict or even feel a shiver of historical echoes when they argue the premise that they (white men) are intrinsically genetically gifted in ways which other groups are not, and that is why they are superior (at technology). Every other time it has ever been argued, it has been false.
Unless the argument was that white men are better at the combination of having penises, privilege, and low amounts of melanin --- we have that hat trick down.
I wasn't arguing the "women aren't good at programming" position.
My personal opinion is that the most important reason there are few women programmers, next to which any other factor fades into insignificance, is that women are simply less interested in doing it. Now that I think about it, the fact that there used to be many more women programmers when women's career options were more limited is pretty strong evidence that this is true: Now that women have more options, there are fewer women programmers.
http://rarlindseysmash.com/images/entries/degrees.png This is a graph that shows the percent of women receiving degrees in each field - you'll notice that there is a peak and then a sudden drop off for computer science. Though, for actual numbers in the 1970's a lot of programmers in general weren't getting CS degrees.
When computer programming first became a thing mostly women had been taught to type. Men would dictate, women would type things up. Think Mad Men.
It was assumed that programming would be basically the same thing. Male mathematicians would write up algorithms and women would type them up. If you read math papers that relied on computer calculation from the 50's and 60's you'll often see women's names in the acknowledgments for having programmed the algorithms.
As it became clear that it was a more involved job, men began moving into the field. Someone else in these comments listed the books that describe the process.