Why do all the articles in same papers reiterate over and over how women still do lion's share of housework? Because the guys are, quite simply not good at it?
It's not so much that men aren't good at housework, Eva, but they just don't feel the necessity of it, as women TEND to. (All of these statements are generalised, Clive, and there will always be many exceptions.) So if the kitchen sink is full of dishes, men TEND to feel easier about leaving them there than women do. Men of course can be trained to do such things (for instance, I would never leave my mother's kitchen in a mess, because I know it would make her unhappy. My filth is confined entirely to my own quarters.)
But the biggest element in time for women would surely have to be children. And until the full-term test-tubes babies come on line, I can't see this factor changing. It is the main element, I think, in all of the questions you ask above.
Here is an interesting discussion, with some more stats.
http://feminism.suite101.com/article...f_womens_roles