Variations within genders.
"Boys and girls perform largely the same in math and science in K-12".
I have some problems with that particular statement. Although I have little doubts that boys and girls could have similar capabilities in STEM at the end of K-12 education, it has not been my experience that boys and girls perform the same throughout K-12 education. Girls, being able to mature faster during the elementary school age, tend to outperform boys in all matters of subject. Upon middle or junior high school, boys usually manage to catch up in capabilities and perform similarly as girls, and then during high or senior high school, via either nurture, culture or the supposedly inherent ability among boys, move ahead on STEM subjects.
The thing I am trying to stress here is that girls and women ought to be given the opportunities to succeed, but ignoring the existing differentiated conditions upon the sexes posed by either society or culture is not the way to go. Simply expecting a woman or a man do the same job the same way that used to be in opposite sex domain is not reasonable nor practical.