@RoamingMillennial Sorry after re reading my last comment, It does sound a bit condescending. I do not mean that no one likes science in absolute. My point is that people who look at STEM fields only on the surface often time do not have any idea what they entail. For someone to really appreciate science it takes hours upon hours of studying and making your brain hurt. It's not something that you can just pick up like a hobby. I am doing a PhD in Chemistry and only after years of academic courses I can start to appreciate the field. When someone learns a new fun fact about molecules and then says "I love Chemistry!", they have no idea what they are getting themselves into. This is my whole point on that, STEM is a lot lot harder that it appears.
Another aspect of the STEM fields is that they are impersonal, and this is why I believe girls do not favor them that much. By impersonal I mean that the human aspect of subjectivity is mostly removed from STEM. If you were to read a research paper on a philosophy or a psychology journal, the tone of that paper will sound as if you are talking to another person. Or you can feel that a human being has written it. When it comes to reading science papers that human element is completely removed, and it sounds like a robot wrote it.
I believe that in this country girls on average tend to be more social than boys in junior high and all the way to high school, and this is perhaps why they favor STEM fields less. For this reason they might want fields that emphasize human socialization not objectivity like in STEM.
As far as there being institutional barriers for women to get into STEM, I have not yet seen any evidence. If someone has it, please link it. I know that there is a discrepancy in the numbers but perhaps correlation is not causation. That is literally the first thing you learn when studying the social sciences.