NPR spent some time on the subject of the decline of women in computer science. Whereas the the percentage of women in other technical fields rose, the percentage of women in computer science declined, as shown in the chart above. Although it's tough to pinpoint a single factor, the time of decline coincides with when computer were mostly marketed towards boys in the 1980s.
In the 1990s, researcher Jane Margolis interviewed hundreds of computer science students at Carnegie Mellon University, which had one of the top programs in the country. She found that families were much more likely to buy computers for boys than for girls — even when their girls were really interested in computers.