Well, how about another factor to consider?
The will to explore. Is it more instilled in men than in women? The need to see over the next hill, past the next river, look beyond the horizon, go into space...is this drive deeper in men?
For example: It's the early 1800's and 10 men and 10 women are in St. Louis. If a poll were taken, how many women vs men would vote to go west? The dangers of heading to California were well known, but I suspect the men ignored the risk (or had the "it can't happen to me" syndrome) and the women were thinking "cold, starvation, indians, disease, no shopping, etc). It is not that they were less interested in the land, the wealth, the new beginning but perhaps, the drive (motivation) factor may have been less...they probably went for the very same reasons some women try diving today...because they supported their men's dreams; not because it was their idea. Men, in general, are not capable of the same level of support on subjects they don't do themselves...don't know why. Our need to see over the next hill can get men into trouble with their SO's...especially if that hill is another woman!
Diving may be the "threshold" sport for women in relationships with men. Golf, tennis, mountain biking, etc are all pretty standard for M/F involvement. But diving? Every trip in is a new exploration with a lot of time and energy needed to make it work. Maybe this is where the line often gets drawn?