Sitting at a computer for 10 hours a day isn't a gendered thing.

There is nothing about computer science or programming that is gender specific. It, ideally, should sit around 50-50, ±5%. So yes, it is a problem that it so heavily skews male.

As to why, it's multi-faceted cultural issue, with how our society treats boys and girls starting from birth. In other words, a pipeline issue.