This whole endless search for the reason why "women aren't in computing" is just a modern day version of epicycle theory. In ancient times, they couldn't admit that the earth went around the sun, so they came up with the increasingly baroque epicycle theory, where planets were postulated to do loop-de-loops just so that no one would have to concede heliocentrism.
Today we face a similar taboo, held for similar quasi-religious reasons. Our latest epicycle is competitive job postings. This at least is laudably specific; most of these kinds of explanations aren't testable at all.
The obvious but taboo answer is that women will generally gravitate to fields which are more social/people focused and less technical/mathematical. That spectrum runs from teaching through medicine in the middle through CS.
These trends are due in nontrivial part to genetics. Women are just more social and men more systematizing, on average.
As programming went from rote punch card/data entry to something more like physics or math, the percentage of women dropped.
All this breast beating is about a refusal to accept that basic biological differences could possibly affect behavior. Indeed, not even the tenured President of Harvard can broach the topic, even if he only moots the possibility of differences in variance rather than mean!
It's not much of a debate when those who voice the "partially genetic" position are at risk of losing their jobs.
Just pointing this out as a woman who is in CS. There is rampant sexism within the field on the lower tier levels.(Still in school so I have yet to deal with higher level positions) Your grunt programmers, techs, and general support staff are down right scary. I have been hopping around company to company for a bit now and some of the places are just down right creepy. I worked one job where open sexism was encouraged and there was a massive boys club mentality. There was one guy who kept joking about how sexy I was and pulled pulled on my hair whenever he walked by.
Also as a whole I have found that even if I am more knowledgeable than everyone around me, I still have people come up and in some of the most condescending ways possible. Many times I am talked down to like I am some sort of child. (I once had someone try to explain how multicast and ssl works to me. They are studying for their A+, I am about to get my CCNP and also churning out all sorts of neat code for our department to help automate a lot of the boring tasks.)
I would say its not so much a genetic issue, but more the field itself has many cultural issues it needs to get past.
Last note: Filing complaints about a lot of these problems would most likely hurt me in the long run. I figured out after my first couple jobs it is easier to ignore them than try to find a new job.
Edit: Regarding skills themselves. It is a much simpler answer to claim that society 'encourages' woman into positions. Even if there was such a gap (Not saying it may not exist mind you) their would still be tremendous overlap and there would be some males within female bounds and females within the male bounds. The odds of that gap being massive enough to overshadow cultural issues is highly unlikely.
Also these stories are not representative of my whole experience in the field. They have been cherry picked to help illustrate a point.
The condescending thing happens to people in tech all the time regardless of their sex. I have done the same thing to men because I think i'm smarter then everyone and have a big ego. I'm sure there are a few really dumb people who condescend to women particularly, but trust me that it's a bigger problem that everyone does in our industry if they have an ego.
As far as the blatant sexism in every job you work at, that does sound pretty bad. Level 1 techs are (imho) ridiculously crass and politically incorrect, imo because they get paid crap and have a stressful job and you're not going to find pillars of polite society in that kind of environment. In higher level positions I don't think i've ever personally seen an example of sexism directed at female co-workers, though i'm sure it must happen somewhere.
In fact, heh, i've often seen politically-incorrect jokes and sexism amongst guys (because let's face it that's what guys do when they're together in a group) but they explicitly stop as soon as a female is around to prevent her from being made uncomfortable. Granted, it's bad that they're making those jokes whether or not a woman is around, but I think them choosing to censor themselves is a positive thing (because let's face it, there's no way to change the thought process of a sexist, but you can at least prevent them from speaking or acting out based on their thoughts).
Your argument falls apart when you posit "worse at math" as an essentialist trait caused by genetics, without so much as a link to a single study showing this. Saying "Women are just more social on average" does not prove that it is genetic.
You can probably name at least one woman amazing at math, or one woman amazing at programming. The fact that you can name even one counterexample refutes the proposition that all women are predisposed against mathematical thinking genetically.
For references on the biology, read Simon Baron-Cohen or Louann Brizendine.
Regarding your statistical "argument", obviously the example of Lisa Leslie does not mean the median height of women is greater than or equal to the median height of men. Overlap does not imply equality.
I often wonder why people who can understand fine statistical distinctions in other contexts, and are capable of calculating over/under representations down to three decimal points, lose about 50 IQ points on this topic.
It is similar to the selective and highly asymmetric demands for evidence. I assure you, there are reams of papers on Pubmed concerning the effect of fetal testosterone levels on spatial reasoning. Indeed, there are many more such technical papers than there are well-controlled studies on the disparate impact effects of "competitive job postings".
This hard evidence differential obtains in spite of the fact that researchers must conduct their studies under dark of night, lest they meet the fate of Larry Summers.
The Wikipedia category for Women mathematicians [1] has 125 pages, many of which are to women who were not professional mathematicians.
If in response to the challenge "name at least one woman amazing at math" you don't think of Emmy Noether, then you are not all that interested in maths.
I've studied math. The most recent mathematician I can recall by name (due to a few important theorems) has been doing his great work in the 1930s. Most of the stuff is older. I don't care squat about the gender, but they're likely all male.
Looking at gender ratios in students it's about 50-50 now (ETH Zürich, Switzerland), massively thinning out towards the top (professors are just a few out of 50). It'll take time and untill female mathematicians have an about equal importance in the curriculum students learn, likely a few hundres years. Maths really ages slowly (often because theories get update/extended, but the name sticks).
So being able to name female mathematicians imo doesn't have much relevance to the gender discussion. Luckily society changes faster than math ages ;-)
Today we face a similar taboo, held for similar quasi-religious reasons. Our latest epicycle is competitive job postings. This at least is laudably specific; most of these kinds of explanations aren't testable at all.
The obvious but taboo answer is that women will generally gravitate to fields which are more social/people focused and less technical/mathematical. That spectrum runs from teaching through medicine in the middle through CS.
These trends are due in nontrivial part to genetics. Women are just more social and men more systematizing, on average.
As programming went from rote punch card/data entry to something more like physics or math, the percentage of women dropped.
All this breast beating is about a refusal to accept that basic biological differences could possibly affect behavior. Indeed, not even the tenured President of Harvard can broach the topic, even if he only moots the possibility of differences in variance rather than mean!
It's not much of a debate when those who voice the "partially genetic" position are at risk of losing their jobs.