Sometimes at my new work I spend a great deal of time reading building code and Material Safety Data Sheets. Surprisingly enough, I actually found that interesting, at least for a certain time span.
It used to be that things buildings- and construction- related were mysteries to me, falling into this realm of mystically un-knowable knowledge that most males all seemed to just be born with, but most females were automatically never to touch. Not like there was anything overt about that, it was just stuff men knew about and little girls like me didn't. Any information about these things that I overheard were all carried on by men who I was less comfortable around anyway so why would I want to join in as a shy little girl, plus they all contained references to this whole network of information I just had no access to, so of course couldn't contribute, so of course felt confused by and never particularly confident about these topics when they came up later in my life.
It turns out I just had to have somebody explain to me what the jargon means, what tools exist and how they are used, what practices are followed, etc. The difference between knowing and not was just that: taking the time to acquire the information, and most importantly, learning it from someone who recognized that I just hadn't learned it yet, not who assumed I didn't know because I was stupid, or a girl and thus stupid.
If we don't teach girls technical things, then of course they aren't going to know technical things, because you have to learn about something to know about it. It's not some inherent gender difference, it's not some inborn differentiation of knowledge, it's just whether you bothered to learn or not, and somebody who already knew bothered to help you learn.
Any inborn inherent stuff that might shape this situation could come from gendered tendencies to think differently due to physically different brain wiring, perhaps leading to different levels of interest in the information. I'm not entirely convinced that that is enough of an explanation in itself, because does interest drive exposure, or does exposure drive interest? There's more than one way to think through any sort of problem, and while people have natural strengths and weaknesses, we've seen that the brain is plastic enough to get good at many things with practice--as long as you do, actually, have a chance to practice and not just hold the flashlight. I didn't give a damn about cars and houses when I was little: I wanted to run into the woods and write stories in my head--although I did also want to build forts and a tree house and I liked my lego set a lot. So I wasn't exposed to fixing cars or building stuff because I wasn't really interested, and if my dad needed help, he asked me to hold the flashlight. If I had been pushed into doing these things instead of just passively watching, as I had been pushed into doing other things that I am now confident in my ability to do, would I have been more interested, and thus know more than I do today about them?
Who the heck knows, and who really cares. The point is, like I read in a National Park Service pamphlet on communicating science: "If you don't know how to fix a car, you're not stupid, you just didn't learn how to do it yet." Don't assume you can't do something just because you haven't learned about it before, and just because there are plenty of other people who have and you aren't like them. You aren't like them, in the sense that you haven't tried and they have. So try.