In this study, 213 American, 229 British, and 164 Japanese students estimated their own multiple IQ scores and that of their parents (mother and father) and siblings (first and second brother and sister). A Sex×Culture ANOVA on the three factors that underlie the seven intelligence types (verbal, numerical, cultural) showed consistent culture and many sex effects, but no interactions. Male participants rated their own overall IQ and that of their fathers, but not their mothers and sisters, higher than did female participants as predicted. Male participants also rated their numerical IQ, but not verbal or cultural IQ, higher than females. There were consistent and clear culture differences. The Americans rated their multiple IQ scores higher than the Japanese (around 6–10 points) with the British intermediate between the two. All participants rated their fathers' (and brothers') numerical IQ higher, and verbal IQ lower, than their mothers' and sisters', as found previously. Overall results showed consistency in the sex differences in ratings across cultures but differences in level of estimated IQ, possibly as a result of cultural demands for modesty.