I chose to do my first programming class when I was 16. The students were virtually all male. Nobody who signed up for that course had the slightest idea about how to program, let alone what programming culture was like. So you want me to believe that all the girls in my grade went out to different jobs, experienced a culture of misogny and then decided not to enroll in programming because of that?
I can tell you why most of the males were in my class and that's because we were all the kids who would sit around at lunch and talk about computers or videogames.
You were 16 at a time when "we were all the kids who would sit around at lunch and talk about computers or videogames". You are not old enough to remember a time when there were not enough kids talking about computers or video games for there to be a group of them chatting over lunch. You are not old enough to remember a time before there was a programmer/gamer culture. For you, it's always been that way, and it's always been a boy's thing. It's no surprise there were no girls in your group.
Kids don't talk about accounting or engineering or nursing or law over lunch. Not that I know of, anyway. They didn't used to talk about computers, either. It wasn't until the 80's that computers became a mainstream entertainment medium. It wasn't until the 90's that programming was common among high-school aged kids. And in the 90's the internet turned any discussion of computers or video games into a boy's thing.
Prior to that women could show up to a college (or high school) programming class on equal footing. Since then, they've learned that programming is a boy's thing. If they think they're going to buck that trend all they have to do is show up at a place like slashdot (or a gaming website) to be discouraged.