Oh you mean just like: "Nice women don't want the vote!".

The problem is that women are the bearer of children and still predominantly the primary childcare provider. Their prime child bearing years coincides with the time when they're academic careers are just starting to get underway. If they take a break for children they loose the momentum in their careers and many male academics don't take them seriously as they believe they aren't 100% committed to academia. Their options then become forgoing having a family or having their careers sidelined.