First, the engineering gap is not hidden. It's extremely obvious. In 10 years of sysadmin/IT work, I've never had another female in the IT/systems groups I've worked in. I've worked in edu, consulting, high tech start ups. I have a BSCS and noticed that there were only 10 other females in my graduating class (out of ~100). I have also noticed that it is a very western thing for females not to be interested in CS/EE. I have met many, many Indian and Chinese women in engineering with CS or EE backgrounds. They seem not to have any of these "inborn" differences than western women have.
So what if baby girls like to play with dolls and baby boys play with trucks. That says nada about future aptitude for CS or EE. I am the mother of a girl, and she loves playing trains and trucks and thinks dolls are a lot of fun to throw down the stairs while yelling "uhoh, my baby!". Basically, even if the brains are wired differently, I don't think it's enough of a difference to make technical work a non-starter for all females. There are some advantaged being socialized female brings to technical work; such as the ability to enjoy taking showers on a daily basis. As a sysadmin, I have noticed that users are often relieved when I work on their issues, instead of the BOFH type who is smug and condescending in his treatment of users.
I am a self taught sysadmin, I worked for 6 years before going back to school to get my CS degree. I think the main reason why we lack distaff autodidacts is that they simply do not have the confidence with machines in our culture that males do. I remember learning pascal (yes, i'm ancient) and my dad telling me "Pascal?! What is that crap, if you were a boy you'd be writing compilers in assembly" when I was 14. If that's not one of those hidden sexist cultural things which undercut one's self confidence, I'm not sure what is. I have been a linux user since 1997, and have attended several LUGs only to be hit on, disregarded, or publicly sexually harassed when giving presentations (on vi of all subjects!). It doesn't really make me want to have a lot do with LUGs.
Another issue I have observed is that males are protective of their in-groups in a professional and scholastic setting. These in-groups tend to make up the talent pool which upon which future start-ups are formed. In school we had several group projects, and none of the males in the top 2/3s of the class wanted me on their team, despite the fact that I usually placed in the top 5 on coding assignments(in class sizes of 60). It was like the third grade all over again. So there is a lot of self-segregation taking place. In fact, I'm not even sure why I'm writing this as these threads usually turn into a misogynistic circle jerk among the dominant male in-group of slashdot (and yes, I've seen many of these types of threads over the years around here).
FWIW, I totally disagree with changing classes to be more "girl" friendly as TFA suggests, that's bogus. Algorithms and computational models were my favorite classes, despite being "dry" or "boring". Math departments didn't paint math pink to get up to 30% female (3x higher than CS/EE by most counts). It's a cultural issue which must be addressed. And you can start by taking down the pr0n in the computer labs(yes, there was pr0n printed out and posted in my undergraduate computer labs, boys will be boys, right?!)
OTOH, I've found my career in IT to be satisfying and worth the trouble. It has the flexibility and high pay that a new mom needs, ironically enough. Try finding that in "women's work".