We have seen self-assessment bias before. Self-assessment of intelligence falls closer to this. Many studies have shown this bias affects men and women differently. And this led to the term MHFH or Male Hubris, Female Humility in cognitive psychology. Note that this exists despite countless studies which failed to find any difference in the levels of general intelligence between men and women.
Apart from these so-called Dunning–Kruger effects, cultural stereotypes play a role in this gender bias. For example, there are study results in which the participants rated their fathers as more intelligent than mothers. Asking parents about their children also resulted in similar impressions. You add teachers, media, or the society as a whole, to this mix; the disaster is complete.
Higher self-esteem is also seen as a contributing factor to higher self-estimations. And gender, as a sex or a personality trait, masculine vs feminine, has a role in this.
