I don't know what they're talking about. Women tend to be attracted to the life sciences. If you look at the numbers of women in medical school or in doctoral programs in the biological sciences, or if you look at the citations in major journals, you'll see a lot of women. Women like studying living things; it's in our genes. Not many of us like rocks, physics, and math (though my cousin does physics at a major university).
Many women also don't do as well with spacial relationships than men do, so we are also less attracted to chemistry and physics.
I do think expectations have something to do with it. I know families in which there are very, very bright, talented girls who are sincerely interested in the sciences and would like to be physicians or researchers, but are actively discouraged by less-educated, unsupportive parents.
I think elementary teachers (don't have experience with older teachers yet) are also not very supportive of boys or girls that are good in math and science.