A question I've often wondered is: why is it that CS has this stereotype much more than biology or chemistry? In the past, say, 50 years those two fields have seen dramatic increases in the relative fraction of women, but CS not as much.
I'm actually not going to answer the "why does CS have this stereotype more" part of the question - I wish I could. Instead I'll float one theory I've heard to answer the second part. One way Bio/Chem/Math/Physics is different than CS is that students mostly don't have experiences with the other sciences outside of the classroom, so everyone is on an even playing field. CS on the other hand became a possible household activity when the personal computer boom happened (around the mid 80s). So while women were on an equal playing field with men in terms of experience with computers in the 80s, by the early 90s this had changed drastically. This possibly causes societal norms to come into play more than if CS were only a classroom thing. Perhaps this is one of the causes for the number of women in the field not increasing in the same way it is in the other sciences.
But that's all guesswork. What's known is this, a Stanford CS Education study discussing gender stereotypes about computer science:
Many of these stereotypes are reinforced by the students previous computer knowledge. More than 75% of the boys in the introductory computer science class had reported using computers before high school, whereas only 20% of the female students reported similarly.
These stereotypes were also seen in the home. Parents were more likely to encourage their son's computer interest over their daughter's. Often the family computer is kept in the boy's room instead of in a common space or in the girl's room. Many girls reported that their brothers had computers at home but they rarely were allowed to use them. Girls mentioned more often in interviews that they wished they had a computer at home, whereas boys were more likely to report having a computer at home that they rarely used.
Since girls were neither encouraged by parents or teachers they often resorted to working on their own in computer science classes. Even in classes in which group work and interaction was the norm, the girls were very often isolated from the rest of the group. Studies have shown that isolated individuals tend to be evaluated more extremely than those in a large group of people. So not only were girls often discouraged from pursuing computer science, but they were often evaluated more critically.
There were also comments on the last post mentioning that this was depressing. Perhaps those people now feel even more depressed. Instead, I believe that it's important to recognize and name these societal problems. I believe the identification is itself useful and empowering. It's also the first step towards change.