Go take a look at the amount of men in the business of midwifing, it's even worse.

Is there anything that prevent a men to work in this field ? I know a guy who did, so I can tell you: Nothing.

If we lack of women in CS it's mostly because women themselves thinks it's not attractive, just like they don't see trucker, or construction worker as attractive jobs. For the same reason teaching, widwifing, etc lack of mens.

IHMO: It's the culture that drive the inbalance in a given field, and the inbalance that create some macho mens, not the other way.