Purpose and significance: Research shows that people hold subjective beliefs about their intellectual levels as well as others. The purpose of this study was to investigate people’s perceptions of intelligence level by gender. Method: A survey questionnaire was developed by a panel of expert through the review of related literature to collect data about family members’ perceptions of each other’s’ intelligence. Participants included 308 people (female = 172; male = 136) whose ages ranged from 14 to 78 (mean = 32, SD = 15). Of the participants 76 were mother, 78 were father, 121 were son, 156 were daughter, 60 were both mother and daughter, and 63 were both father and son. The questionnaire consisted of eight items: ratings of their own intelligence level as well as intelligence levels of their spouses, parents and children. A likert-type scale was used for rating from 1 to 5 (ex-tremely below average, below average, average, above average, extremely above average). Results: In comparing the judgments of individuals regarding their own intelligence levels by gender, it was seen that the difference between the estimates of individuals from different genders about their own intelligence levels was not significant statisti-cally (t = -1.07, p > 0.05). A comparison between the participants’ ratings of their own intelligence levels and those of their spouses’ intelligence levels showed no signifi-cant difference (t = 0.09, p > 0.05). Analysis of women’s ratings for their own intelli-gence levels and their husbands’ intelligence levels also showed no significant difference (t = -1.09, p > 0.05). Similarly, analysis of men’s ratings for their own intelligence levels and their wives’ intelligence levels yielded no significant difference (t = 1.17, p > 0.05). The most important finding of this study was that parents rated their male children to be more intelligent than their female children. The difference was significant (t = -2.98, p < 0.05). However, the effect size of this difference was small (2 = .21). Further analysis showed the difference came from fathers’ ratings. That is, fathers rated their sons more intelligent than their daughters (t = -2.21, p < 0.05). Effect size of the dif-ference was found to be small (2 = .26). Mothers’ ratings did not make a difference. Analysis of children’s estimates regarding their parents’ intelligence levels yielded no significant difference between their estimates of intelligence levels of their moth-ers and those of their fathers (t = -0.64, p>0.05). Furthermore, female children’s ratings of intelligence levels of their mothers and those of their fathers, and male children’s ratings were compared. Neither analysis showed a significant difference (t=0.00, p>0.05).The participants’ estimates regarding intelligence levels of their siblings were com-pared generally. The difference between participants’ evaluations regarding intelli-gence levels of their sisters and those of brothers was not statistically significant (t = -1.47, p > 0.05). Furthermore, although both sisters and brothers assessed their broth-ers to be more intelligent, the difference was not significant (t = 0.77, p > 0.05). That is, neither brothers rated their male siblings more intelligent than their female sisters or vice versa nor sisters rated their female siblings more intelligent than male siblings or vice versa. Discussion and Conclusions: Sons were rated more intelligent than daughters by their fathers in this study. Other studies about family members’ ratings of each oth-er’s intelligence levels show a different picture. More gender differences were ob-tained in these studies. Findings usually favor sons and fathers. That is, there might be a gender bias against daughters and mothers. Could this bias affect parent in-vestments in education opportunities that they provide for their children?