The trouble with boys, say a couple of new studies, is that they have too much confidence. It seems that an average boy is likely to believe that he is smarter than average while average girls are less likely to. Lots of studies show that this effect is pervasive in women of all ages - at least above the age of 5. Moreover, confidence is known to play a big role in success, even though the Dunning-Kruger effect is in action (less competent persons are more likely to overestimate their competence than the more competent. Anyone who doubts these two principles should consider the case of our chief executive.
So does this pervasive effect just reflect the ongoing success of the patriarchy in keeping the womenfolk down, or is there a biological basis? My guess would be a bit of both. Boys who lack confidence are urged to "grow a pair." Girls wind up growing pairs of organs that don't produce testosterone. The most demanding and prestigious jobs in society require confidence and assertiveness, and even very talented women are often reluctant to compete for them.