Yes. A much higher proportion of women than men chose to stay at home and a much higher proportion of women than men chose to work in part-time jobs; you could argue that the cultural factors responsible for this are examples of discrimination, but only with great difficulty and certain unfortunate implications.
Yeah of course. It is just that that statement is one of those statements which may be true but would be impossible to find out by any sort of realistic method. I would not rule it out though and I would not consider it a sign of "stupidity".
I threw that one in there because I knew someone would bite.
What makes it stupid is mostly the second part which is a really, really stupid blanket statement. The implication is that if there was no discrimination then every profession would have the exact same division of all groups. Which is completely ridiculous. Now, given the right sort of qualifications (along the lines Al suggest, for instance) it isn't necessarily stupid. But the analysis pretty much begins and ends with that quote. And that is breathtakingly shallow.
I mean, for starters there are many groups and many professions where this is obviously untrue (such as physically very demanding jobs, for instance). So, in order to make this claim one must first explain why leadership positions and gender stand out in this respect.