Evolution is the simple and scientifically plausable answer. Men who are successful in competitive ventures are seen as prefferable mates to females and that has caused a drive in men to "win" that women have less of. Men generally don't look at competitive success as a high priority in potential mates and as such it is not a genetically enhanced thing in females.
Women are less competive at sports for the same reason that male deer grow huge antlers to fight other males with while female deers do not. The male birds with crazy plummage to attract females of the same species who do not have the same elaborate feathers.
Males of every species have competition driven into them by evolution to attract mates, females not nearly so much and not in the same way at all.
The same line of reasoning can be used to point out that not only do men have more of a competitive drive than woman, but they also by and large have better hand eye coordination. Throughout history men have been relied on to hunt, fish, build, fight and defend. So all else being equal, men are at an advantage in this department. This is not to say that there aren't women that are very coordinated, or even some that are less coordinated but are able to overcome this through hard work. But the numbers will always be in our favor. Or at least, for the next few thousand years.
As far as the break is concerned, it really depends on what game you are talking about. In ten ball, I think the men have a huge advantage. 9 ball not so much.
Overall, I think men have much more powerful strokes than do the women. However, this difference is difficult to see due to the fast cloth that is now typical on any tournament table. However, think about it this way for a second: When a woman is faced with a long difficult pot, that she has to draw the cue ball back say 3/4 the length of the table, can she do it? Of course she can. However, this type of shot is probably going to be pushing her to the limits of her stroke's ability. Now when a top male pro is faced with a similar shot, he will only be stroking at say 70 percent of his total ability. While this difference in stroking ability doesn't show up each and every rack, it does show up over the long run if you pay close attention.
So it's the difference in the stroke that makes the men better than the women in the long run. I don't really know, but I bet this difference showed up much more clearly in the pre Simonis days.
