It could be because of systemic factors like how we raise boys and girls differently. That’s what we said when girls were behind, so I’d give the same benefit of doubt to boys now.
Raging lib here: not every disparity is due to sexism.
Impossible to tell without more information. I was in a class where the women's GPA was much higher than the men's GPA, but that was because there was only one woman in the class and she was an absolute stud.