It seems that strictly hierarchical systems, such as military officers and clergy, are practically entirely dominated by males. When you include historical examples from around the world, the skewedness of these hierarchies towards male members is - in my estimation - too strong to be entirely cultural.

It'd be easy to come up with evopsych narratives to make this plausible (along the lines of the Expendable Male argument), but I think the sociological/historical evidence is strong enough by itself.