It's not that testosterone and estrogen don't exist. It's the conceptual leap that testosterone and estrogen explain why women go into one work field versus another. Especially when those proportions vary dramatically across countries. (Do Iranian women, where the majority of STEM majors are women, have different estrogen than American women?).
It sounds like Iran is suffering from a terrible gender imbalance in STEM majors. Is anything being done to correct this problem?
"Third world" enrollments might not be a valid comparison as STEM is seen as a road to riches. A valid comparison would be a country where women have the privilege of choosing to not seek money.