The question then becomes why interest isn't shown in the first place.
You could argue, as the "manifesto" writer did, that there's some kind of innate biological explanation. To me, that's a pretty extraordinary claim and requires extraordinary proof. It's true that there are some differences between the sexes. Women do a bit better on some mental tests than men and vice versa. But how much of that is biology and how much is upbringing? For instance, from an early age, studies show parents make girls say "please" more than they do for boys, and emphasize sharing. So do women fair better on some emotional tests because of some innate biology or because we've emphasized that kind of thing literally since they could talk? It's really really hard to tease these things apart. And it's so hard because those differences are tiny. If we assumed those differences really are 100% biological (again, a big assumption), it might explain why Computer Science would be 55% men, and 45% women. It wouldn't explain the huge disparity we see today.
So if the reason women don't show interest isn't biological, what is it? A further complicating factor to the whole discussion is we're talking about why women aren't in computer science now. It hasn't always been this way. Historically, the field of computing had lots of women. A lot of women went from "human computers" who did math by hand to programming the early mainframes (the movie Hidden Figures shows a time at NASA when this was happening). While a gender gap has always existed, it used to be a lot smaller. Women made up about 1/3 of people with CS degrees in the late 70s and early 80s. But as the STEM gender gap has been closing everywhere else, it's actually gotten wider in CS, and only CS. Why? The "it's biology and girl brains are different" argument can't account for that. Biology didn't change.
What did change was society. Movies like Weird Science and War Games (my favorite) came out. The "cool hacker" entered Pop culture, and the stereotype they settled on was a boy. Girls were a lot less likely to have computers in the home as well. This is an interesting article (http://www.npr.org/sections/money/2014/10/21/357629765/when-...) that talks about how early home computers were marketed as a toy to buy for boys.
It's like we as a society decided that computers fell into the "boy stuff" category with GI Joe and baseball, not the "girl stuff" category like Barbie and softball.
I think it all adds up to a pretty convincing argument that biology has nothing (or very, very little) to do with it.