the objective of the study was to investigate the relationshipbetween childhood iq of parents and characteristics of their adultoffspring. it was a prospective family cohort study linked to amental ability survey of the parents and set in renfrew and paisleyin scotland. participants were 1921-born men and women who took partin the scottish mental survey in 1932 and the renfrew/paisley studyin the 1970s, and whose offspring took part in the midspan familystudy in 1996. there were 286 offspring from 179 families. parentaliq was related to some, but not all characteristics of offspring.greater parental iq was associated with taller offspring. parentaliq was inversely related to number of cigarettes smoked byoffspring. higher parental iq was associated with better education,offspring social class and offspring deprivation category. therewere no significant relationships between parental iq and offspringsystolic blood pressure, diastolic blood pressure, cholesterol,glucose, lung function, weight, body mass index, waist hip ratio,housing, alcohol consumption, marital status, car use and exercise.structural equation modelling showed parental iq associated withoffspring education directly and mediated via parental social class.offspring education was associated with offspring smoking and socialclass. the smoking finding may have implications for targeting ofhealth education.