(My comment, repeated from the other similar thread that got go superseded by this one)
The problem of getting anyone, young or adult, interested in a subject --any subject-- isn't one with a simple solution. Technical subjects have the added difficulty that they require you to use your brain in non-trivial ways. Given equal exposure to the subject matter, I fail to see how a male or female subject would react differently to the idea of learning that subject. This, of course, assuming that both the male and female subjects got to that moment in time with a similar educational and perhaps even cultural frame of reference. If a mother only ever bought a little girl frilly pink and shiny things, well, it is probably unlikely that as a teenage girl or an adult woman she would even remotely show interest in learning more technical subjects. She will probably be a dancer and go into the arts or some other less "brainy" occupation. That's not to say that there aren't exceptions to this, but they are probably few and far between.
The same is true of boys. If they are brought-up in front of a playstation, shooting at things, playing sports, and well outside of more academically focused areas he will probably grow up to be a jock and then move on to careers that do well when you use half your brain. Hell, he might even go into sales! Things are vastly different if you feed your kids a constant diet of what they should be learning in order to operate at a different level when they are older. My teenage son finished MIT's CS 6.00.1x course just a few weeks ago. That did not happen magically. That was a lot of work. For me and for him! And that also required a lot of work to get to the point where he could even be shoved into that end of the pool.
My little girl is too young to think about formal learning of these kinds of subject, but this year she got introduced to Lego robotics and is starting to like it. Yet, the situation is exactly the same: It requires a ton of time and dedication on my part --as the designated nerd at home-- to keep her exposed to such subjects and make it fun. I have to get silly while teaching something useful. I have to figure out ways to make robotics fun, silly, exciting and something she wants to do. We don't buy lots of silly frilly things for her. That said, I have to tell you, it is hard to fight both genetics and exposure to such things through her peers.
I guess my message is that parents needs to be very engaged and active in bringing up a child into the sciences and technology. It will not happen by osmosis. And, I really don't think gender makes a huge difference. It might change the approach, but I don't think it is the primary determinant of success or failure. One way I've explained this in the past to friends who marvel at what my kids are doing is that this is like a Formula 1 car drafting a car in front of them. You need to drive well and use a lot of effort to get close enough to be within the zone where drafting happens. Up until that point you are using a lot more energy to chase the car in front of you. Once you get into the drafting zone you need less power to maintain the same speed. Yet, you still need that foot solidly planted on the accelerator.
With kids you have to push, push, push. I have navigated through really frustrating moments when I've gotten angry because I couldn't understand why he (my oldest son) didn't just grab that book I bought for him and launched himself into software development nirvana. Of course, I always reflected upon these things and never externalized them --not much of a motivator to yell and scream at your kid about learning something-- and realized that (a) he is still young and (b) we are not in the "draft zone" yet. It'll take a lot more effort --and this is different from kid to kid-- to get him into the "draft zone". Once we reach that zone it will require a lot less energy on my part and, if interested, he will ultimately need virtually no support from me.
This is where I look at some of the things being said about STEM education and can't help but think we are just throwing money into a big bonfire. You can't force people into learning anything. A lot of my kid's friends are, well, jocks or exhibit no interest in anything at all. They are navigating through school with no guidance or encouragement in any direction whatsoever. You can't just throw money at that and expect things to change. For most kids it requires far more work than can be done during the time they are at school. Yes, of course, there are a few kids in every sample group that need almost zero work. These kids get hooked on a subject like programming and just go, go , go. Most kids are not like that. Just like most successful businesses did not get launched with a long coding session over a weekend while eating popcorn.
Going back to my little girl, she is not seriously exposed to Lego robotics. In fact, our living room table is an official FLL table with the official field mat and everything. Yes, we are serious about this. I'd rather have a learning environment in my living room than a fancy dinning room table. As far as why there aren't more women in tech today. I don't have the answer for that. I only know that when I was a teenager girls mostly did different stuff. Not because they were being forced away from tech, they simply showed no interest in what we were doing. My guess is that it all came from home. So, as our culture changes so will that aspect of things.
Evolution?