Associations between some polymorphic markers and variation in IQ and its components in otmoor villagers

Data on variation in eight polymorphic marker systems and some psychometric traits collected for other purposes in a group of Oxfordshire villages were examined for possible associations. Of a number that appeared statistically significant, one between haptoglobin and aspects of Wechsler Adult Intelligence Scale (WAIS) IQ seemed particularly interesting, since the haptoglobin variation is also associated with "within family" social mobility. After using a multiple regression approach to allow for the possible effects on IQ of sex, geographical location, social class, and family structure, the association between haptoglobin and performance IQ became even stronger. This procedure removed the evidence for all the other associations except for one between Kell blood group and IQ. When the haptoglobin variation was examined in relation to the component subtests of the WAIS, the association turned out to arise entirely from the block design element.