"Same as above; women aren't usually natural leaders."
Beliefs like this are inherently sexist. And dis-empower women.
It is highly likely the leadership is one of those qualities which has a social dimension. So it is how you are raised that makes you likely to exhibit leadership qualities.
If you are called a bitch for telling people what to do, but the boys doing the same are not, you tend to be less vocal and get less experience being a leader (as a child).
There is ample evidence that if women speak 50% of the time (in meeting or similar business contexts) that they are precieved as taking over. (discusses widely in articles like this: http://inthesetimes.com/article/16157/our_feminized_society
“If there's 17 percent women, the men in the group think it's 50-50,” she told NPR. “And if there's 33 percent women, the men perceive that as there being more women in the room than men.” )
It is more correct to say, we* have trained our women to be quiet and not have their voices heard, because this makes it easier to control them.
Than to say they are 'naturally'** not leaders.
*Where 'we' is the patriarchy.
** Whatever naturally means, we are naturally social animals, we naturally form groups, we naturally develop cultural norms, and there are numerous examples of 'natural' matriarchies where women are the leaders.